serial: fsl_lpuart: Remove unnecessary clearing for CRTSCTS

if (termios->c_cflag & CRTSCTS) guarantees that CRTSCTS is not ever set
in the else block so clearing it is unnecessary.

While at it, remove also one pair of extra parenthesis.

Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220513082906.11096-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>