[Intel-gfx] [PATCH 0/2] Track calls to intel(_logical)_ring_{begin, advance}

[Dave Gordon]

When adding instructions to a legacy or LRC ringbuffer, the sequence of
emit() calls must be preceded by a call to intel(_logical)_ring_begin()
to reserve the required amount of space, and followed by a matching call
to intel(_logical)_ring_advance().  Historically some (display) code
didn't use begin/advance, but just inserted instructions ad hoc, which
would then be sent to the hardware along with the current or next batch,
but this is not supported and is now regarded as incorrect.

This commit therefore adds begin/advance tracking, with WARNings where
various forms of misuse are detected.