regulator: pbias: program pbias register offset in pbias driver

Add separate compatible strings for every platform and populate the
pbias register offset in the driver data.
This helps avoid depending on the dt for pbias register offset.

Also update the dt binding documentation for the new compatible
strings.

Suggested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/Documentation/devicetree/bindings/regulator/pbias-regulator.txt b/Documentation/devicetree/bindings/regulator/pbias-regulator.txt
index 32aa26f..acbcb45 100644
--- a/Documentation/devicetree/bindings/regulator/pbias-regulator.txt
+++ b/Documentation/devicetree/bindings/regulator/pbias-regulator.txt
@@ -2,7 +2,12 @@
 
 Required properties:
 - compatible:
-  - "ti,pbias-omap" for OMAP2, OMAP3, OMAP4, OMAP5, DRA7.
+  - should be "ti,pbias-dra7" for DRA7
+  - should be "ti,pbias-omap2" for OMAP2
+  - should be "ti,pbias-omap3" for OMAP3
+  - should be "ti,pbias-omap4" for OMAP4
+  - should be "ti,pbias-omap5" for OMAP5
+  - "ti,pbias-omap" is deprecated
 - reg: pbias register offset from syscon base and size of pbias register.
 - syscon : phandle of the system control module
 - regulator-name : should be