[media] exynos4-is/media-dev: get rid of a warning for a dead code

drivers/media/platform/exynos4-is/media-dev.c: In function 'fimc_md_link_notify':
drivers/media/platform/exynos4-is/media-dev.c:1102:4: warning: suggest braces around empty body in an 'else' statement [-Wempty-body]
    ; /* TODO: Link state change validation */
    ^

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>