staging: easycap: group module parameters handling

1. For readability group module parameters handling on one place
2. Introduce kernel config option EASY_DEBUG

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