tty: serial: amba-pl011: fix miscellaneous checkpatch warnings

tty: serial: amba-pl011: fix miscellaneous checkpatch warnings

Fix the following messages from checkpatch:

    $ ./scripts/checkpatch.pl --strict --file \
        drivers/tty/serial/amba-pl011.c

    ERROR: do not initialise statics to false
    WARNING: Possible unnecessary 'out of memory' message
    WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
    WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then
             dev_info(dev, ... then pr_info(...  to
    CHECK: Prefer using the BIT macro

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20231207-mbly-uart-v6-6-e384afa5e78c@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>