headers_check fix: alpha, statfs.h

fix the following 'make headers_check' warning:

  usr/include/asm-alpha/statfs.h:6: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

arch/alpha/include/asm/statfs.h

 #ifndef _ALPHA_STATFS_H
 #define _ALPHA_STATFS_H
 
+#include <linux/types.h>
+
 /* Alpha is the only 64-bit platform with 32-bit statfs. And doesn't
    even seem to implement statfs64 */
 #define __statfs_word __u32