[ARM] pxa: include <mach/hardware.h> in pxa-regs.h

for the reference of __REG() within <mach/hardware.h>
Signed-off-by: NEric Miao <eric.miao@marvell.com>

arch/arm/mach-pxa/include/mach/pxa-regs.h

@@ -13,6 +13,7 @@
 #ifndef __PXA_REGS_H
 #define __PXA_REGS_H
 
+#include <mach/hardware.h>
 
 /*
  * PXA Chip selects