iommu/arm-smmu: fix stale fault reporting in ecats operation

If FSR is not cleared before starting ECATS operation, non-zero FSR cause
successful ECATS operation to be reported as failed. Also, resume any
faulting transcation before halting TBU.

Change-Id: I46955d0a75660fbbee09468140301ab9b10a699e
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>