sif: rq: Do not clear the rq_sw until the completion of flush_rq

sif: rq: Do not clear the rq_sw until the completion of flush_rq

Orabug: 23754857

The rq can be invalidated from reset_qp or flush_rq. Nevertheless,
the rq_sw data structure has been reset after rq is invalidated in
reset_qp regardless of the completion of the flush_rq. Thus, move
the rq synchronization to reset_qp, and place the synchronization
in between of reset_qp and flush_rq. After invalidating and
reseting the rq, no flush rq is required as both head and tail
have been reset to 0.

This commit creates another atomic_t variable for the synchronization
between reset rq and flush_rq.

Signed-off-by: Wei Lin Guay <wei.lin.guay@oracle.com>
Reviewed-by: Knut Omang <knut.omang@oracle.com>