OMAP4: PM: Handle LPDDR CLK IO errata during suspend/idle

There is a HW bug in CMD PHY which gives ISO signals as same for
both PADn and PADp on differential IO pad, because of which IO
leaks higher as pull controls are differential internally and
pull value does not match A value.
Though there is no functionality impact due to this bug, it is
seen that by disabling the pulls there is a savings ~500uA in
OSWR, but draws ~300uA more during OFF mode.

To save power during both idle/suspend following approach taken:
 1) Enable WA during boot-up.
 2) Disable WA while attempting suspend and enable during resume.

CDDS no: OMAP4460-1.0BUG00291
(OMAP official errata ID yet to be available).

Change-Id: Ic39f17be50ff602c71e714b05af3811b35c1a67f
Reported-by: Logan Lee <hklee@ti.com>
Signed-off-by: Shashi Shekar B.S. <shashi.shekar@ti.com>
Signed-off-by: Ambresh K <ambresh@ti.com>