Merged in david_s5/nuttx/master_stm32_f4_i2c (pull request #490)

stm32:stm32f40xxx I2C ensure proper isr handling

Injecting data errors that causes a STOP to be perceived by the
   driver, will continually re-enter the isr with SB not set and BTF
   and RxNE set.  This changes allows the interrupts to
   be cleared and  propagates a I2C_SR1_TIMEOUT to the waiting task.

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