ARM: 8756/1: NOMMU: Postpone MPU activation till __after_proc_init

ARM: 8756/1: NOMMU: Postpone MPU activation till __after_proc_init

This patch postpone MPU activation till __after_proc_init (which is
placed in .text section) rather than doing it in __setup_mpu. It
allows us ignore used-only-once .head.text section while programming
PMSAv8 MPU (for PMSAv7 it stays covered anyway).

Tested-by: Szemz? András <[email protected]>
Tested-by: Alexandre TORGUE <[email protected]>
Signed-off-by: Vladimir Murzin <[email protected]>
Signed-off-by: Russell King <[email protected]>