Also redefine GPIOs even after WDS canned config.
Also enable more ints.

add success checks in packet handler config
enable pullups on gpios
add code to customize irq enabling
setup rx_start to go back to rx on rx timeout.
display more int status

Per Matias Edlund:  I recently used the tcflush function and found that it failed with ENOTTY. The reason is that the TCFLSH case in the function uart_ioctl in the file drivers/serial/serial.c does not update the ret value."  On success, the TCFLSH IOCTL logic needs to explicitly set the return value (ret) to zero.

drivers/sensors/sht21:  Change I2C_TRANSFER return value so that it return on zero on success, not the count of bytes transferred.

lots of small misc changes
conditional storage of int status
custom irq setting
cut long lines and add {}
add bit definitions for int definition
upper half: manage read timeout

drivers/serial/Kconfig:  Kconfig is too big, divide into Kconfig, Kconfig-uart, Kconfig-usart, Kconfig-sci, Kconfig-16550.  More than one MCU supports LPUARTs.  Add Kconfig-lpuart and remove MCU-specific LPUART definitions.  Affects Kinetis and STM32L4.

drivers/lcd/ft80x:  Fix a typo that caused the driver to fail to recognize the ft801 chip version. Also update an unrelated README file.

    drviers/lcd/ft80x:  No longer depends on CONFIG_EXPERIMENTAL
    Update README.txt

    drivers/lcd/ft80x:  ACTIVE host command appears to be formatted differently than other host commands; Fix ROM CHIPID.  Appears to be big-ending, BCD.
    drivers/lcd/ft80x:  Fix some compile issues when debug features are enabled.

drivers/net/phy_notify.c:  Use phy debug macros instead of net debug macros.  ninfo() and nerr() are used a bit too much, so the console output is difficult to read with network debug.

Feature pca9540bdp i2cmultiplexer

* Implement common i2c multiplexer abstraction to be reused by i2c multiplexer devices. Provide common interface with transfer and reset calls to set up virtual i2c busses.

* Remove i2cmux_lower_half.c and headers, will be implemented by each mux driver

* Implement PCA9540BDP I2C multiplexer lower half which uses the common i2c mux abstraction

* Remove application interface and implement common i2c functions

* Remove application interface from pca driver and implement common i2c functions directly in the pca driver

* Use i2cerr

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Per OpenGroup.org, syslog -- and, hence, nonstandard vsyslog, and debug wrappers -- does not return a value.  Rename _vsyslog to nx_vsyslog.  Use internal nx_vsyslog in the few cases where a return value is required.

Fix some errors found in build testing + clean-up some issues with last changes to remove use of printf() from within the OS.

Remove all usage of printf() from the OS.  That is not an acceptable context for the use of an application-oriented interface that depends on a task-specific file descriptor and C buffered I/O.