ARM: dts: msm: update TADC ibatt scale for MSMCOBALT

Currently when the battery is charging (sinking current) the ibatt is
positive. Change the scale polarity so that ibatt is negative when
the battery is charging.

Change-Id: I431dcc766df94adb7ee85d4cb32d9181a74d871a
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>