arm: Fix setjmp (again)

Commit e6777248 (arm: Fix setjmp) added code to fix compilation of the setjmp
code path with thumv1. Unfortunately it missed a constraint that the adr
instruction can only refer to 4 byte aligned offsets.

So this patch adds the required alignment hooks to make compilation
work again even when setjmp doesn't happen to be 4 byte aligned.

Signed-off-by: Alexander Graf <agraf@suse.de>
Tested-by: Tom Rini <trini@konsulko.com>