ARM: asm/pl080.h: Protect against multiple inclusion of header file

<asm/hardware/pl080.h> doesn't have protection to deal with multiple inclusion.
And so we get compilation errors in cases where this file is included more than
once. This patch adds #ifdefs at the top of file to protect it against multiple
inclusions.

Signed-off-by: Viresh Kumar <[e-mail]>
Acked-by: Linus Walleij <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

arch/arm/include/asm/hardware/pl080.h

···
  * OneNAND features.
 */
 
+#ifndef ASM_PL080_H
+#define ASM_PL080_H
+
 #define PL080_INT_STATUS			(0x00)
 #define PL080_TC_STATUS				(0x04)
 #define PL080_TC_CLEAR				(0x08)
···
 	u32	control1;
 };
 
+#endif /* ASM_PL080_H */