ARM: PJ4: remove the ARMv6 compatible cache method entries

The Marvell PJ4 is ARMv7 capable, so we don't support it in
ARMv6 mode anymore.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Acked-by: Saeed Bishara <saeed.bishara@gmail.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>