drm/sched: Rename to drm_sched_can_queue()

Rename drm_sched_ready() to drm_sched_can_queue(). "ready" can mean many
things and is thus meaningless in this context. Instead, rename to a name
which precisely conveys what is being checked.

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Alex Deucher <Alexander.Deucher@amd.com>
Link: https://lore.kernel.org/r/20230517233550.377847-1-luben.tuikov@amd.com