[media] easycap: cleanup function usage

1. Remove declarations of none global functions from easycap.h
and make them static in the c-files.
2. Reorder static functions to reduce number of forward declarations.
3. Remove unused functions.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
5 files changed