ARM: dts: msm: Modify GPU IB vote as per new DDR clk plan

Change GPU IB voting values w.r.t. modified DDR clock plan.
Old Values: 331MHz (SVS), 662MHz( Nominal)
New Values: 350MHz(SVS), 700MHz(Nominal), 748MHZ(Nominal+)

Change-Id: I939afdd1b78177b36dcf1821e2f13fe504f6f1e1
Signed-off-by: Anshuman Dani <adani@codeaurora.org>