broadcom/vc4: Fix use-after-free for flushing when writing to a texture.

broadcom/vc4: Fix use-after-free for flushing when writing to a texture.

I was trying to continue the hash table loop, not the inner loop.  This
tended to work out, because we would have *just* freed the job struct.
Fixes some valgrind failures in fbo-depthtex.

Fixes: f597ac396640 ("vc4: Implement job shuffling")
(cherry picked from commit d88a75182d5fccb956fbfccddf627aa1831465be)