ARM: OMAP2+: Fix build issues with missing include of linux/bug.h

Otherwise we can get the following if bug.h is not included from kernel.h:

arch/arm/mach-omap2/powerdomain-common.c:
In function 'omap2_pwrdm_get_mem_bank_onstate_mask':
arch/arm/mach-omap2/powerdomain-common.c:64:3: error:
implicit declaration of function 'WARN_ON' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
diff --git a/arch/arm/mach-omap2/powerdomains3xxx_data.c b/arch/arm/mach-omap2/powerdomains3xxx_data.c
index 8ef26da..b7ea468 100644
--- a/arch/arm/mach-omap2/powerdomains3xxx_data.c
+++ b/arch/arm/mach-omap2/powerdomains3xxx_data.c
@@ -13,6 +13,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/bug.h>
 
 #include <plat/cpu.h>