[PARISC] Fix HPUX compat compile with current GCC

GCC no longer allows a cast as lvalue; fix the same way fs/readdir.c was
Signed-off-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

arch/parisc/hpux/fs.c

@@ -96,7 +96,7 @@ static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 	put_user(namlen, &dirent->d_namlen);
 	copy_to_user(dirent->d_name, name, namlen);
 	put_user(0, dirent->d_name + namlen);
-	((char *) dirent) += reclen;
+	dirent = (void __user *)dirent + reclen;
 	buf->current_dir = dirent;
 	buf->count -= reclen;
 	return 0;