[media] s5p-csis: Add explicit dependency on REGULATOR

The driver used the regulator API so it should depend on REGULATOR.

[mchehab@redhat.com: break depends on on two lines, instead of using a \]
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>