[media] rc-core: rename dev->scanmask to dev->scancode_mask

We already have dev->scancode_filter and dev->scancode_wakeup_filter
so rename dev->scanmask to dev->scancode_mask for consistency.

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>