commit a1480dcc upstream.

Accessing do_remount_sb should require global CAP_SYS_ADMIN, but
only one of the two call sites was appropriately protected.

Fixes CVE-2014-7975.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>