[POWERPC] remove include of asm/of_device.h from pmi.h

pmi.h does not diectly reference anything in of_device.h and of the two
files that include asm/pmi.h, one includes of_device.h and the other
includes of_platform.h (which includes of_device.h).
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/pmi.h

@@ -29,8 +29,6 @@
 
 #ifdef __KERNEL__
 
-#include <asm/of_device.h>
-
 #define PMI_TYPE_FREQ_CHANGE	0x01
 #define PMI_READ_TYPE		0
 #define PMI_READ_DATA0		1