[media] exynos4-is: Fix error paths in probe() for !pm_runtime_enabled()

Ensure clk_disable() is called on error paths only when clk_enable()
was previously called.

This fixes following build warning:

.../media-git/drivers/media/platform/exynos4-is/fimc-lite.c: In function 'fimc_lite_probe':
.../media-git/drivers/media/platform/exynos4-is/fimc-lite.c:1583:1: warning: label 'err_sd' defined but not used [-Wunused-label]

Reported-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>