ARM: dts: am33xx-l4: fix UART compatible

ARM: dts: am33xx-l4: fix UART compatible

Fixes the following dtschema check warning:

serial@0 (ti,am3352-uart): compatible: 'oneOf' conditional failed, one must be fixed:
	['ti,am3352-uart', 'ti,omap3-uart'] is too long
	'ti,am3352-uart' is not one of ['ti,am64-uart', 'ti,j721e-uart']
	'ti,am654-uart' was expected
	from schema $id: http://devicetree.org/schemas/serial/8250_omap.yaml#

Signed-off-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Reviewed-by: Judith Mendez <jm@ti.com>
Link: https://lore.kernel.org/r/20250721173741.6369-1-bruno.thomsen@gmail.com
Signed-off-by: Kevin Hilman <khilman@baylibre.com>