iommu: arm-smmu: reset CBn FSR while device reset

commit 8cd0b952aaa9 ("iommu/arm-smmu: add DT option to skip certain
initialization"), skipped FSR clearing at the time of device reset. This
works if HW resets FSR. Otherwise FSR may have unknown value out of device
reset, this can cause spurious fault when context bank is enabled. Clear
any pending faults in CBn FSR while device reset.

Change-Id: I8402f77958a29b40e8119528eed432ada1414d6b
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>