[media] s5c73m3: fix indentation of the help section in Kconfig

The 'help' section of the Kconfig entry for this driver is missing
an extra alignment. That seems to violate what's stated at:
	Documentation/kbuild/kconfig-language.txt

Even if it works, the better is to add 2 extra spaces there, as
this is the common practice and helps human reading of the file.

Also, the way it is, it breaks backport trees.
Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>