i965/gen9: Add XY_FAST_COPY_BLT support to intelEmitCopyBlit()

i965/gen9: Add XY_FAST_COPY_BLT support to intelEmitCopyBlit()

This patch enables using XY_FAST_COPY_BLT only for Yf/Ys tiled buffers.
It can be later turned on for other tiling patterns (X,Y) too.

V3: Flush in between sequential fast copy blits.
    Fix src/dst alignment requirements.
    Make can_fast_copy_blit() helper.
    Use ffs(), is_power_of_two()
    Move overlap computation inside intel_miptree_blit().

V4: Use _mesa_regions_overlap() function.
    Add check for src_buffer == dst_buffer.
    Simplify horizontal and vertical alignment computations.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>