[media] s5p-fimc: Fix return value of __fimc_md_create_flite_source_links()

Make sure 'ret' is not used uninitialized.

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>