staging/easycap: replace NOREADBACK with moduel parameter

NOREADBACK doesn't justify Kconfig option so we use module
paramter for it.

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