mips: add entry for new mlock2 syscall

A previous commit introduced the new mlock2 syscall, add entries for the
MIPS architecture.

Signed-off-by: Eric B Munson <emunson@akamai.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/mips/kernel/scall32-o32.S

@@ -594,3 +594,4 @@ EXPORT(sys_call_table)
 	PTR	sys_execveat
 	PTR	sys_userfaultfd
 	PTR	sys_membarrier
+	PTR	sys_mlock2