Code-paths responsible for initializing CPU's stack pointer and variable
used in stack memory resource reservation got out of sync which resulted
in actual stack being 64K off from what "stack" struct resource
registered by arm_request_stack() thought it was.

At least one issue resulting from that can be easily triggered by
running:

memtest -t

This commit unifies the aforementioned code to a certain degree which
solves the problem and hopefuly makes it less likely to become an issue
again.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>