ARM: dts: omap4-sdp: remove unneded unit names

This patch fixes the following DTC warnings for omap4-sdp.dtb
and omap4-sdp-es23plus.dtb:

"encoder@0 has a unit name, but no reg property"
"endpoint@0 has a unit name, but no reg property"
"connector@0 has a unit name, but no reg property"

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>