1. add functions check kernel enable a ring or not.
2. add function gem_get_num_rings() to check how many rings kernel has
enable.
3. gem_ring_sync_loop.c will call gem_get_num_rings() directly instead
of original static fucntion get_number_rings().
Signed-off-by: Zhong Li <zhong.li@intel.com>
[Ben: Wrapped commit message + whitespace fixes]
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>