ARM: dts: msm: Update ldo-delta for 8974Pro and APQ8084 based devices

The procedure of generating the voltage frequency table has changed in
a way such that we could potentially undervolt the CPU while in LDO mode.

Change the ldo-delta-voltage parameter for these devices from 50mV to
25mV.

CRs-Fixed: 569190
Change-Id: Ic814ac449a8a7f1ba41462127aa43153bef67441
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>