UART_IBRD, UART_FBRD, and UART_LCR_H form a single 30-bit wide register which
is updated on a single write strobe generated by a UART_LCR_H write. So, to
internally update the content of UART_IBRD or UART_FBRD, a write to UART_LCR_H
must always be performed at the end.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
Acked-by: Simon Glass <sjg@chromium.org>