sink plugin: fixed kms sink compile error
sink plugin: fixed kms sink compile error

Added missing drm/kms cflags & ldflags in kms/Makefile.am.

Signed-off-by: Sandeep Sheriker Mallikarjun <4cb7efb7ec7146b20b6723a387e7b188e835a8cb@microchip.com>

linux4sam/gst1-hantro-g1,linux4sam/gst1-hantro-g1