This backports upstrem NuttX
ea7b673 - Allow dma in 1 bit mode in STM32F4xxx
17cbec1 - fix warning from ea7b673
4795d58 - Only the decoded.oid = (cid[0] >> 8) change.
Thanks to Jussi Kivilinna
https://bitbucket.org/nuttx/nuttx/commits/9169ff6a15fe65ba4af134b470dbf89220274c19
stm32_serial: fix freezing serial port. Serial interrupt enable/disable functions
do not disable interrupts and can freeze device when serial interrupt is received
while execution is at those functions.
Trivially triggered with two or more threads write to regular syslog stream and to
emergency stream. In this case, freeze happens because of mismatch of priv->ie
(TXEIE == 0) and actually enabled interrupts in USART registers (TXEIE == 1),
which leads to unhandled TXE interrupt and causes interrupt storm for USART.
Daniel Agar