tty: serial: amba-pl011: avoid quoted string split across lines

Remove all instances of quoted strings split across lines. Fix four
checkpatch warnings:

    $ ./scripts/checkpatch.pl --strict --file \
        drivers/tty/serial/amba-pl011.c
    WARNING: quoted string split across lines
    [...]

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
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-v6-4-e384afa5e78c@bootlin.com


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