stm32_i2c_alt:Move def of regval to top func def per CS

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

Upstream stm32 build fixes

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

Merged in david_s5/nuttx-14/david_s5/stm32f7stm32_allocateheapc-there-are-5-c-1490226997884 (pull request #290)

stm32f7:stm32_allocateheap.c There are 5 configurations

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

STM32 Flash fixes

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

This is a know hardware issue on some STM32 see the errata of your model
and if you make use of both memory banks you should enable it.

Writing to a flash sector while starting the erase of other sector
have a undefined behavior so lets add a semaphore and syncronize
access to Flash registers.

But for the semaphore to work it needs to be initialized so each
board needs call stm32_flash_initialize() on initialization, so
to avoid runtime problems it is only using semaphore and making
it thread safe if initialized, after all boards starts to call
stm32_flash_initialize() we can remove the boolean and the check.

Erase a sector from the second bank cause the bit 4 of SNB being set
but never unsed, so trying to erase a sector from the first bank
was acually eraseing a sector from the second bank.

Kconfig: Change the minimum SMP_NCPUS to 1

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

drivers/lcd/st7565.c: Use ST7565_POWERCTRL_INT instead of ST7565_POWERCTRL_BRF

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