[media] media: rc-core: use %s in rc_map_get() module load

rc_map_get() takes a single string literal for the module to load,
so make sure it cannot be used as a format string in the call to
request_module().

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>