fix(st-uart): correctly fill BRR register

To get the nearest divisor for BRR register, we use:
Divisor =  (Uart clock + (baudrate / 2)) / baudrate
But lsl was wrongly used instead of lsr to have the division by 2.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: Iedcc3ccdb4cf8268012e82a66df2a9ec48fc1d79
1 file changed