arm: armv8: mmu: add mem_map_from_dram_banks

arm: armv8: mmu: add mem_map_from_dram_banks

For armv8, U-Boot uses a static map defined as 'mem_map' for configuring
the MMU as part of mmu_setup.

But since the exact configuration of memory banks might not be known at
build time, many platforms such as imx9, versal2 etc. utilize
gd->bd->bi_dram to configure the static map at runtime.

Therefore this patch adds a new API mem_map_from_dram_banks that
modifies the static map in a similar way. Allowing the caller to map all
dram banks by just passing the index to last entry in their mem_map and
it's length.

Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Anshul Dalal <anshuld@ti.com>
Tested-by: Wadim Egorov <w.egorov@phytec.de>