USART_CR1_M combines both USART_CR1_M0 and USART_CR1_M1 macros
affecting bits 12 and 28 on 7 data bits capable UARTs. Whereas
for other UARTs USART_CR1_M macro affects only bit 12.
This patch fixes wrong data bits usage on 7 data bits capable
UARTs with using USART_CR1_M0 macro for modes 8-E-x and 8-O-x.
It also simplifies bits unsetting as USART_CR1_M macro clears
all data bits related bits for both UART types.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
ca8f74a0b0