ARM: mm: dma-mapping: Separate gap-page from num-pf-page

ARM: mm: dma-mapping: Separate gap-page from num-pf-page

A mapping can have gap-page and num-pf-page mentioned separately.
However, the current code adds a prefetch page for iommu mapping
if gap-page is 1 even though num-pf-page is 0. This is wrong and
prefetch page should not be mapped. Fixing it with this change.

Bug 200070960

Change-Id: I76fccbf9feb34d1dfd284d4ac48565dd21257864
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Reviewed-on: http://git-master/r/669775
Reviewed-by: Hiroshi Doyu <hdoyu@nvidia.com>
GVS: Gerrit_Virtual_Submit