tty: max3100: remove unused variable rts and remove unused assignment

tty: max3100: remove unused variable rts and remove unused assignment

Variable rts is being assigned but it is never read, hence it can be
removed.  The assignment to param_new to zero is redundant as it is
being updates a few statements later, so remove this redundant
assignment. Cleans up two clang warnings:

drivers/tty/serial/max3100.c:277:3: warning: Value stored to 'rts'
is never read
drivers/tty/serial/max3100.c:439:2: warning: Value stored to 'param_new'
is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>