platform/x86: barco-p50-gpio: Fix duplicate included linux/io.h

Clean up the following includecheck warning:
drivers/platform/x86/barco-p50-gpio.c: linux/io.h is included more than once.

No functional change.

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Acked-by: Peter Korsgaard <peter.korsgaard@barco.com>
Link: https://lore.kernel.org/r/1648021825-6182-1-git-send-email-baihaowen@meizu.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>