iommu/arm-smmu: Drop devm_free_irq when driver detach

There is no need to call devm_free_irq when driver detach.
devres_release_all which is called after 'drv->remove' will
release all managed resources.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>