[ARM] arm32: Merge v7 mmu and v5 mmu to reduce redundancy.

This patch merges v7 mmu support and v5 mmu support to reduce redundancy.

The v7 mmu is backward compatible to v6 mmu so, the merged mmu support is actually for v5, v6 and v7 processors

Signed-off-by: Anup Patel <anup@brainfault.org>