[media] exynos4-is: Enable fimc-is clocks in probe() if runtime PM is disabled

Ensure the device works also when runtime PM is disabled. This will
allow to drop an incorrect dependency on PM_RUNTIME.

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