[media] exynos-gsc: Fix checkpatch warning in gsc-m2m.c

Fixes the following warning:
WARNING: space prohibited between function name and open parenthesis '('
FILE: media/platform/exynos-gsc/gsc-m2m.c:606:
	ctx = kzalloc(sizeof (*ctx), GFP_KERNEL);

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>