[POWERPC] Use FIELD_SIZEOF in arch/ppc

Robert P.J. Day proposed to use the macro FIELD_SIZEOF in replace of code
that matches its definition.

The modification was made using the following semantic patch
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
type t;
identifier f;
@@

- (sizeof(((t*)0)->f))
+ FIELD_SIZEOF(t, f)

@depends on haskernel@
type t;
identifier f;
@@

- sizeof(((t*)0)->f)
+ FIELD_SIZEOF(t, f)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/ppc/8xx_io/commproc.c

@@ -43,7 +43,7 @@
 ({									\
 	u32 offset = offsetof(immap_t, member);				\
 	void *addr = ioremap (IMAP_ADDR + offset,			\
-			      sizeof( ((immap_t*)0)->member));		\
+			      FIELD_SIZEOF(immap_t, member));		\
 	addr;								\
 })