ARM: dts: am437x-l4: fix typo in can@0 node

Replace clock-name with clock-names.

Fixes: 2a4117df

 ("ARM: dts: Fix dcan driver probe failed on am437x platform")
Signed-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Tony Lindgren <tony@atomide.com>