staging/easycap: make ALSA ops function static in sound.c

1. make also ops function static
2. move around code so to avid forward declarations

Cc: Mike Thomas <rmthomas@sciolus.org>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>