ARM: sunxi/dt: make the CHIP inherit from allwinner,sun5i-a13

The sun4i-timer driver registers its sched_clock only if the machine is
compatible with "allwinner,sun5i-a13", "allwinner,sun5i-a10s" or
"allwinner,sun4i-a10".
Add the missing "allwinner,sun5i-a13" string to the machine compatible.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: 465a225f ("ARM: sun5i: Add C.H.I.P DTS")
Cc: <stable@vger.kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>