cygnus: enable mmu

this is not only for speed but also preventing the cpu from crashing.
the cpu is not happy when cache is cleaned without mmu turned on.

BUG=chrome-os-partner:36691
BRANCH=broadcom-firmware
TEST=boot purin to romstage.

Change-Id: I2445dcc2729798c4fc56fa191cbc8471ef708d08
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 9e35c925b75213e1d35bf191f22c39aaf1726eeb
Original-Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Original-Change-Id: Icaf8c506df258edb99413949e6e3089a2b1a91af
Original-Reviewed-on: https://chrome-internal-review.googlesource.com/199388
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Commit-Queue: Daisuke Nojiri <dnojiri@google.com>
Original-Tested-by: Daisuke Nojiri <dnojiri@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/251306
Reviewed-on: http://review.coreboot.org/9768
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
2 files changed