ARM: dts: msm: Change FG cut-off voltage to default for SDM660 QRD

In the new SDM660 QRD devices, PM660 does not need the hardware
workround that cut-off voltage should be set to 3.7V, so delete
the qcom,fg-cutoff-voltage property.

CRs-Fixed: 2013279
Change-Id: Ica55128a2f426a668b0d43d04424e13672dd78fd
Signed-off-by: Yingwei Zhao <cyizhao@codeaurora.org>