video: fbdev: controlfb: Fix set but not used warnings

video: fbdev: controlfb: Fix set but not used warnings

[ Upstream commit 4aca4dbcac9d8eed8a8dc15b6883270a20a84218 ]

The controlfb driver has a number of dummy defines for IO operations.
They were introduced in commit a07a63b0e24d
("video: fbdev: controlfb: add COMPILE_TEST support").

The write variants did not use their value parameter in the
dummy versions, resulting in set but not used warnings.
Fix this by adding "(void)val" to silence the compiler.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patchwork.freedesktop.org/patch/msgid/20201206190247.1861316-13-sam@ravnborg.org
Signed-off-by: Sasha Levin <sashal@kernel.org>