Implement __raw_{read,write}[bwl] on all architectures

This adds implementations of __raw_read[bwl] and __raw_write[bwl] to
m68k, ppc, nios and nios2. The m68k and ppc implementations were taken
from Linux.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/include/asm-nios/io.h b/include/asm-nios/io.h
index d77695a..08e46a3 100644
--- a/include/asm-nios/io.h
+++ b/include/asm-nios/io.h
@@ -23,6 +23,14 @@
 #ifndef __ASM_NIOS_IO_H_
 #define __ASM_NIOS_IO_H_
 
+#define __raw_writeb(v,a)       (*(volatile unsigned char  *)(a) = (v))
+#define __raw_writew(v,a)       (*(volatile unsigned short *)(a) = (v))
+#define __raw_writel(v,a)       (*(volatile unsigned int   *)(a) = (v))
+
+#define __raw_readb(a)          (*(volatile unsigned char  *)(a))
+#define __raw_readw(a)          (*(volatile unsigned short *)(a))
+#define __raw_readl(a)          (*(volatile unsigned int   *)(a))
+
 #define readb(addr)\
 	({unsigned char val;\
 	 asm volatile(  "	pfxio	0		\n"\