iommu/arm-smmu: Drop if with an always false condition

iommu/arm-smmu: Drop if with an always false condition

The remove and shutdown callback are only called after probe completed
successfully. In this case platform_set_drvdata() was called with a
non-NULL argument and so smmu is never NULL. Other functions in this
driver also don't check for smmu being non-NULL before using it.

Also note that returning an error code from a remove callback doesn't
result in the device staying bound. It's still removed and devm allocated
resources are freed (among others *smmu and the register mapping). So
after an early exit to iommu device stayed around and using it probably
oopses.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20230321084125.337021-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Joerg Roedel <jroedel@suse.de>