OMAP2+: voltage: start towards a new voltagedomain layer

Start cleaning up the voltage layer to have a voltage domain layer
that resembles the structure of the existing clock and power domain
layers.  To that end:

- move the 'struct voltagedomain' out of 'struct omap_vdd_info' to
  become the primary data structure.

- convert any functions taking a pointer to struct omap_vdd_info into
  functions taking a struct voltagedomain pointer.

- convert the register & initialize of voltage domains to look like
  that of powerdomains

- convert omap_voltage_domain_lookup() to voltdm_lookup(), modeled
  after the current powerdomain and clockdomain lookup functions.

- omap_voltage_late_init(): only configure VDD info when
  the vdd_info struct is non-NULL

Signed-off-by: Kevin Hilman <khilman@ti.com>
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index 40b6d47..7c36fde 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -38,6 +38,7 @@
 #include "io.h"
 
 #include <plat/omap-pm.h>
+#include "voltage.h"
 #include "powerdomain.h"
 
 #include "clockdomain.h"
@@ -349,10 +350,12 @@
 		omap243x_clockdomains_init();
 		omap2430_hwmod_init();
 	} else if (cpu_is_omap34xx()) {
+		omap3xxx_voltagedomains_init();
 		omap3xxx_powerdomains_init();
 		omap3xxx_clockdomains_init();
 		omap3xxx_hwmod_init();
 	} else if (cpu_is_omap44xx()) {
+		omap44xx_voltagedomains_init();
 		omap44xx_powerdomains_init();
 		omap44xx_clockdomains_init();
 		omap44xx_hwmod_init();