fs/binfmt_elf.c: remove unneeded initialization of mm->start_stack

As pointed out by zoujc@lenovo.com, setup_arg_pages() already
initialized current->mm->start_stack.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=202881
Reported-by: <zoujc@lenovo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf.c

@@ -884,8 +884,6 @@ static int load_elf_binary(struct linux_binprm *bprm)
 	if (retval < 0)
 		goto out_free_dentry;
 	
-	current->mm->start_stack = bprm->p;
-
 	/* Now we do a little grungy work by mmapping the ELF image into
 	   the correct location in memory. */
 	for(i = 0, elf_ppnt = elf_phdata;