BoardConfig.mk.template: Add TARGET_CPU_SMP

This one is easy forget if not in the template

Change-Id: If65e557a661ecc81c6bfc434525b3c9937ff988e
(cherry picked from commit 469c47b1a8ab96f2000c2a46d5debeb65dbe7c03)
Revert "Specify -mcpu=cortex-a15 for krait CPU variants."

Breaks exfat for some reason. Will check further.
Revert for now.

This reverts commit 137d6986268c7ad2effdf6a6d50b3338b9e2e022.

(cherry picked from commit 87b26fab775f819375453f65e5dece063045b56e)