serial: omap-serial: remove flag from serial_omap_rdi()

The local 'flag' variable carries only TTY_NORMAL. So use that constant
directly and drop the variable.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712081811.29004-10-jirislaby@kernel.org


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