ARM: dts: Fix dm816x to use right compatible flag for MUSB

With commit 3e457371 ("usb: musb: Fix fifo reads for dm816x with
musb_dsps") we need to use the right compatible flag to avoid issues
with FIFO reads.

Cc: Bin Liu <binmlist@gmail.com>
Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: George Cherian <george.cherian@ti.com>
Fixes: 3e457371 ("usb: musb: Fix fifo reads for dm816x with musb_dsps")
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>