fs/binfmt_em86.c: fix incompatible pointer type

Since the -Wincompatible-pointer-types is reported as error, alpha
doesn't build anymore.  Let's fix it in a minimal way.

  fs/binfmt_em86.c:73:35: error: passing argument 2 of `copy_strings_kernel' from incompatible pointer type [-Werror=incompatible-pointer-types]
     retval = copy_strings_kernel(1, &i_arg, bprm);
                                     ^            ^
  fs/binfmt_em86.c:77:34: error: passing argument 2 of `copy_strings_kernel' from incompatible pointer type [-Werror=incompatible-pointer-types]
    retval = copy_strings_kernel(1, &i_name, bprm);
                                    ^

Link: http://lkml.kernel.org/r/1469525978-23359-1-git-send-email-wagi@monom.org
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_em86.c

@@ -24,7 +24,8 @@
 
 static int load_em86(struct linux_binprm *bprm)
 {
-	char *interp, *i_name, *i_arg;
+	const char *i_name, *i_arg;
+	char *interp;
 	struct file * file;
 	int retval;
 	struct elfhdr	elf_ex;