[ARM] arm32: Setup 4KB pages at boot-time instead of 1MB pages

Currently, we create section entries (1MB pages) at boot-time. This
puts constraint that exection start/end (i.e. code start/end) address
have to be 1MB aligned causing waste of memory. Further, arch reserved
area (i.e. L1/L2 ttbl pools) is also 1MB aligned to simplify the
arch_cpu_aspace_primary_init() function but this also leads to waste
of memory in arch reserved area.

This patch updates boot-time code to create 4KB pages instead of 1MB
pages and also removes 1MB alignment restriction in execution start/end
and arch reserved area.

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