[POWERPC] Add signed types to bootwrapper

Add signed types to the powerpc zImage bootwrapper. These are needed by the
PS3 hcall interface.
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/types.h

@@ -7,6 +7,10 @@ typedef unsigned char		u8;
 typedef unsigned short		u16;
 typedef unsigned int		u32;
 typedef unsigned long long	u64;
+typedef signed char		s8;
+typedef short			s16;
+typedef int			s32;
+typedef long long		s64;
 
 #define min(x,y) ({ \
 	typeof(x) _x = (x);	\