dma-mapping-fast: Ensure reserved iovas are actually reserved

"mapping->clean_bitmap" holds the iovas which are currently available.
"mapping->bitmap" holds the iovas which will be available after a tlb
invalidate operation.
For an iova to be reserved properly, it needs to be set in both of the
above bitmaps.

Fixes: 07972090 ("dma-mapping-fast: reduce TLBI during map")
Change-Id: I163e63fd1dfc8161733f56d796a9f0a781fd79b1
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>