mxser: remove else from LSR bits checks

UART_LSR_SPECIAL is composed of UART_LSR_BI, UART_LSR_PE, UART_LSR_FE,
UART_LSR_OE. So status cannot be anything else. Remove the unused else
branch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210618061516.662-18-jslaby@suse.cz


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