[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.