arm: 1M align init, text, rodata if CONFIG_STRICT_MEMORY_RWX is set

Init code, text, rodata and data need different permissions
and so they need to be on different pages. The kernel 1-to-1
mapping is constructed using 1M pages to improve TLB performance
and this should not be changed (to 4K pages). Therefore
ensure that each of these regions starts on a 1M boundary.

Change-Id: I855b58d3deff6c34e58d1cbdef4b360c2b23ca6d
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>
Signed-off-by: Jin Hong <jinh@codeaurora.org>
(cherry picked from commit 4cfee820adbdd7514b67e59c1b87008436d984ab)