OMAP: VP: Explicitly mask VPVOLTAGE field

Reading the VPVOLTAGE field of PRM_VP_*_VOLTAGE registers currently
relies on a u32 -> u8 conversion to mask off the FORCEUPDATEWAIT field
in the upper bits.  Make this explicit using the mask symbol
already defined, added as a new field in struct omap_vp_common.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
diff --git a/arch/arm/mach-omap2/vp44xx_data.c b/arch/arm/mach-omap2/vp44xx_data.c
index 0daf2a4..b4e7704 100644
--- a/arch/arm/mach-omap2/vp44xx_data.c
+++ b/arch/arm/mach-omap2/vp44xx_data.c
@@ -51,6 +51,7 @@
 	.vlimitto_vddmin_shift = OMAP4430_VDDMIN_SHIFT,
 	.vlimitto_vddmax_shift = OMAP4430_VDDMAX_SHIFT,
 	.vlimitto_timeout_shift = OMAP4430_TIMEOUT_SHIFT,
+	.vpvoltage_mask = OMAP4430_VPVOLTAGE_MASK,
 	.ops = &omap4_vp_ops,
 };