arm64: fix missing asm/pgtable-hwdef.h include in asm/processor.h

On next-20150105, defconfig compilation breaks with:

./arch/arm64/include/asm/processor.h:47:32: error: ‘PHYS_MASK’ undeclared (first use in this function)

Fix by including asm/pgtable-hwdef.h, where PHYS_MASK is defined.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 286b1be..e271690 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -33,6 +33,7 @@
 #include <asm/hw_breakpoint.h>
 #include <asm/ptrace.h>
 #include <asm/types.h>
+#include <asm/pgtable-hwdef.h>
 
 #ifdef __KERNEL__
 #define STACK_TOP_MAX		TASK_SIZE_64