ata: pata_parport: fix pata_parport_devchk

There's a 'x' missing in 0x55 in pata_parport_devchk(), causing the
detection to always fail. Fix it.

Fixes: 246a1c4c ("ata: pata_parport: add driver (PARIDE replacement)")
Cc: stable@vger.kernel.org
Signed-off-by: Ondrej Zary <linux@zary.sk>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>