ARM: dts: omap2: add missing unit name to func_96m_ck

This patch fixes the following DTC warnings for omap2430-sdp.dtb:

"func_96m_ck has a reg or ranges property, but no unit name"

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