radv: remove predication on cache flushes

This can lead to a situation where cache flushes could get conditionally
disabled while still clearing the flush_bits, and thus flushes due to
application pipeline barriers may never get executed.

Fixes: a6c2001a (radv: add support for cmd predication.)
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit ef272b16)
[Emil Velikov: trivial conflicts]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

Conflicts:
	src/amd/vulkan/radv_cmd_buffer.c