ARM: dts: Fix typo for dm816x usb0_pins

Commit a54879a0 ("ARM: dts: Fix USB dts configuration for dm816x")
attempted to fix the USB features introduced by commit 7800064b
("ARM: dts: Add basic dm816x device tree configuration") but obviously
I did not read the dmesg as more USB issues still keep trickling in.

It should be usb1_pins instead not usb0_pins for the second interface
to avoid warnings from pinctrl framework.

Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>