Following cleanup of the vga device code in commit d2e043a8,
the arrays dmask4 and dmask16 are now unused. gcc doesn't warn
about this, but clang does; remove them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>