slimbus-msm: Do IOMMU detach as part of power up

Do IOMMU detach as part of power up sequence instead of
power down, to avoid SMMU faults during SSR down while BAM
transactions are active.

Change-Id: If75752992c0156470886f109ca8151d8e3da7bc6
Signed-off-by: Shrey Vijay <shreyv@codeaurora.org>
Signed-off-by: Dilip Kota <dkota@codeaurora.org>