When we attach a device to a domain, we configure the SMRs (if we have
any) to match the Stream IDs for the corresponding SMMU master and
program the s2crs accordingly. However, on detach we tear down the s2crs
assuming stream-indexing (as opposed to stream-matching) and SMRs
assuming they are present.

This patch fixes the device detach code so that it operates as a
converse of the attach code.

Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>