ARM: dts: msm: update ceiling/floor voltages for gfx_vreg in 8996ProAU CDP

The CPR graphics regulator (gfx_vreg) in 8996Pro has an
additional virtual corner to support higher Fmax. Also it has
support for another speed bin. The external buck (hl7509_vreg)
that powers up gfx_vreg in 8996ProAU CDP boards has a voltage
range of 600 to 1230 mV with a step size of 10 mV.

Modify the CPR ceiling and floor voltages of gfx_vreg for 8996Pro
automotive CDP so that they are divisible by 10000 uV and at
least 600000 uV.

CRs-Fixed: 988322
Change-Id: I7841c384b5d10124226c91bd7adc1730461e60ce
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>