arm:board:trats2:FIX: Clear INFORM4 and INFORM5 registers at correct boot

During switch to device tree, commit 1ecab0f3 has removed this code.

INFORM4 and INFORM5 registers are used by TRATS2 first stage bootloader for
providing recovery. For normal operation, those two must be cleared out.

This error emerges when one force reset from u-boot's command line for
three times.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Acked-by: Minkyu Kang <mk7.kang@samsung.com>