arm: dma-mapping: Fix broken iommu attach and detach

'Commit 1748f086 ("arm64: dma-mapping: Support attach
after detach case")' modified the attach detach API framework
for arm64 alone, leaving 32-bit arm into compilation menace.
Hence, fix this.

Change-Id: I7cdeecca599aec4c70cf0aa9d34f5db2d5844f39
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>