regulator: Add MAX77xxx series regulator driver

This driver supports MAX77686 and MAX77802. It does not support DVS and
SELB features of these PMICs.

Original-Change-Id: I59e1b9ac733f40e22308c8c4e8738f09ee429049
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit-int.chromium.org/35507
Reviewed-by: Doug Anderson <dianders@google.com>
Commit-Queue: Doug Anderson <dianders@google.com>
Tested-by: Doug Anderson <dianders@google.com>
(cherry picked from peach-alpha commit
	15a5c42ab9646632adcb68d4692ac9d6b68a75e6)

BUG=chrome-os-partner:19007,chrome-os-partner:18697
TEST=Build and boot on peach-pit and snow.

Change-Id: I12ee38bbc9aaf4e140a6975210e0d4fe2b53bca8
[abrestic: squashed opmode fix, ramp delay fix, addition of low-jitter
mode, and voltage select mask fix]
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/56569
Reviewed-by: Simon Glass <sjg@chromium.org>