dt-bindings: serial: Move omap-serial.txt to YAML schema

Convert serial-omap.txt to YAML schema for better checks and documentation.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20210610182227.2480-1-vigneshr@ti.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>