linux-phytec-fsl

USB: serial: cp210x: clean up CRTSCTS flag code

The CRTSCTS flag code cleared (and inconsistently) bits unrelated to
CRTSCTS functionality. It was also harder than necessary to read.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>