Staging: easycap: Add dependencies to Kconfig

The "depends on" line was inadvertently omitted from the inaugural patch.

Signed-off-by: Mike Thomas <rmthomas@sciolus.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>