ARM: dts: dra7: Increase max-voltage of pbias regulator

As per recent TRM, PBIAS cell on dra7 devices supports
3.3v and not 3.0v as documented earlier.

Update PBIAS regulator max voltage to match this.

Document reference:
SPRUI30C – DRA75x, DRA74x Technical reference manual- November 2016

Tested on:
DRA75x PG 2.0 REV H EVM

Signed-off-by: Ravikumar Kattekola <rk@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>