ARM: OMAP2+: PRCM: cleanup some header includes

Some of the includes are totally unnecessary, remove some others in
preparation to make the PRCM its own driver.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
[paul@pwsan.com: updated to apply; fixed build error on OMAP2xxx-only configs]
Signed-off-by: Paul Walmsley <paul@pwsan.com>
diff --git a/arch/arm/mach-omap2/powerdomain.h b/arch/arm/mach-omap2/powerdomain.h
index da5a59a..f472711 100644
--- a/arch/arm/mach-omap2/powerdomain.h
+++ b/arch/arm/mach-omap2/powerdomain.h
@@ -21,8 +21,6 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
-#include "voltage.h"
-
 /* Powerdomain basic power states */
 #define PWRDM_POWER_OFF		0x0
 #define PWRDM_POWER_RET		0x1
@@ -75,6 +73,7 @@
 
 struct clockdomain;
 struct powerdomain;
+struct voltagedomain;
 
 /**
  * struct powerdomain - OMAP powerdomain