ARM: dts: Correct misspelling, "emda3" -> "edma3"

Correct misspelling, "emda3" -> "edma3".

Reported-by: Adam J Allison <adamj.allison@gmail.com>
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>