OMAP2+: powerdomain: add voltagedomain to struct powerdomain

Each powerdomain is associated with a voltage domain.  Add an entry to
struct powerdomain where the enclosing voltagedomain can be
referenced.

Modeled after similar relationship between clockdomains and powerdomains.
Signed-off-by: Kevin Hilman <khilman@ti.com>

arch/arm/mach-omap2/powerdomain.h

@@ -24,6 +24,8 @@
 
 #include <plat/cpu.h>
 
+#include "voltage.h"
+
 /* Powerdomain basic power states */
 #define PWRDM_POWER_OFF		0x0
 #define PWRDM_POWER_RET		0x1
@@ -78,6 +80,7 @@ struct powerdomain;
 /**
  * struct powerdomain - OMAP powerdomain
  * @name: Powerdomain name
+ * @voltdm: voltagedomain containing this powerdomain
  * @prcm_offs: the address offset from CM_BASE/PRM_BASE
  * @prcm_partition: (OMAP4 only) the PRCM partition ID containing @prcm_offs
  * @pwrsts: Possible powerdomain power states
@@ -97,6 +100,10 @@ struct powerdomain;
  */
 struct powerdomain {
 	const char *name;
+	union {
+		const char *name;
+		struct voltagedomain *ptr;
+	} voltdm;
 	const s16 prcm_offs;
 	const u8 pwrsts;
 	const u8 pwrsts_logic_ret;