headers_check fix: powerpc, bootx.h

fix the following 'make headers_check' warnings:

  usr/include/asm-powerpc/bootx.h:12: include of <linux/types.h> is preferred over <asm/types.h>
  usr/include/asm-powerpc/bootx.h:57: found __[us]{8,16,32,64} type without #include <linux/types.h>

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

arch/powerpc/include/asm/bootx.h

@@ -9,7 +9,7 @@
 #ifndef __ASM_BOOTX_H__
 #define __ASM_BOOTX_H__
 
-#include <asm/types.h>
+#include <linux/types.h>
 
 #ifdef macintosh
 #include <Types.h>