iommu/arm-smmu: Check for static-cb option before requesting TZ

We want to request TZ to change page table format
for non secure context banks only if static-cb
option is enabled. If the option is disabled then
programming of global registers would be done by
HLOS itself and we need not request TZ to change
page table format.

Change-Id: Id2228e6d2ec835e169d679296760256ce0524050
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>