ARM: dts: dra7-evm: Fix typo in SMPS6 (VDD_GPU) max voltage

The max expected voltage for VDD_GPU, connected to SMPS6, is 1.25V.
Correct regulator max voltage constraint to meet this requirement.

Document reference: DRA74 Data Manual, SPRS857M - Dec 2012,
		    Revised Oct 2014.

Fixes: c56a831c

 ("ARM: dts: DRA7: Add TPS659038 PMIC nodes")

Signed-off-by: Ravikumar Kattekola <rk@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>