arm: armv8: mmu: export mmu_setup

arm: armv8: mmu: export mmu_setup

The mmu_setup function configures the page tables based on the board
supplied mem_map struct array. It is called implicitly as part of
dcache_enable but this limits us to only be able to use APIs such as
mmu_change_region_attr only after caches are enabled.

This might lead to speculative accesses before we can unmap a region
that is marked as cacheable in the static memory map.

Therefore this patch exports the mmu_setup function in mmu.h allowing
users to have more control over when the mmu is configured.

For K3 specifically this allows for the following configuration sequence
as part of enable_caches:

static mem_map fixups (TODO) -> mmu_setup -> carveouts using
mmu_change_region_attr (TODO) -> icache/dcache enable

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