Teensy clock fixes.

Added driver of IS25xP SPI flash devices

All configurations that have both CONFIG_NSH_LIBRARY=y and CONFIG_NET=y must now also have CONFIG_NSH_NETINIT=y

Refresh all configurations that have both CONFIG_NSH_LIBRARY and CONFIG_NET set in preparation for another change.

Fix STM32 DMA code and configuration for STM32F37X chips

The High Gain bit in MCG_C1 was preventing teensy from booting
except after a programming session. The second change doesn't appear
to change any functionality, but complies with restrictions in the k20
family reference manual on FEI -> FBE clock transiions.

Based on sst25xx driver

Signed-off-by: Marten Svanfeldt <marten@intuitiveaerial.com>

Signed-off-by: Marten Svanfeldt <marten@intuitiveaerial.com>

assert: Check if NDEBUG is defined

Refactored configs/nucleo-144 sub-directories to support additional nucleo-144 board.  Add support for the Nucleo-F767ZI board.

Add stm32f105r support

Kinetis usb driver

First attempt at a usb device controller driver for kinetis. derived from pic32mx usb driver, which uses the same usb controller.

STM32: Fix typo