Rambi: Enable 32k SUSCLK signal

The SoC needs to provide a 32k clock signal SUSCLK for
some modems to work properly, so this enables the signal.

BUG=chrome-os-partner:24425
TEST=Manual, check SUSCLK pin with a scope.

Change-Id: Ibc0d5bb38a2c3e16f381dfc256097fdced67fd1c
Reviewed-on: https://chromium-review.googlesource.com/180101
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Signed-off-by: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5722
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
Tested-by: build bot (Jenkins)