stagine/easycap: use module paramter for default encoding instead of ifdef

remove PREFER_NTSC ifdef as it cannot be possible put into Kconfig

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