iommu/arm-smmu: Tear down domain context if attach fails

Currently we're leaving domains half-initialized after a
partially-successful attach.  Fix this by destroying the domain in the
error path. This should allow another second attach_dev() call to
potentially succeed.

This differs from the upstream implementation in that upstream seems to
expect a call to domain_free() after a failed attach_dev(). Without
this call flow, an error in alloc_io_pgtable_ops() will cause a bit
from the context bank bitmask to be leaked.

Additionally, do not ignore errors from request_irq().

Change-Id: I36c529ed4974c01fba96088b6f57a8e82b350252
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>