staging/easycap: remove oss support

remove support for OSS. OSS is being deprecated
and it is just plain headache to support both alsa and oss.

Last I broke the compilation when OSS is enabled with the patch
cdaa898b5efcc598ab1004e8f913061dc7005091
staging/easycap: kill telltale logic

so this fixes also that issue.

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