ARM: dts: am437x-cm-t43: Use a correctly spelled DT property

Back in 2014 a property got misspelled "ti,coordiante-readouts" instead
of "ti,coordinate-readouts".

The year after it got fixed but both are still supported, although this
is not a reason to continue using this old deprecated property.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>