serial: imx: do not disable individual irqs during termios change

imx_set_termios(): disabling individual interrupt requests in UART for
duration of the routine is pointless. Get rid of it.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-4-git-send-email-sorganov@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>