ARM: dts: socfpga: Remove unneeded unit names

Node eccmgr has a unit name, but do not have a reg property as only the
child nodes do have this property. Likewise the usbphy node do not have
a reg property. This will trigger the following warnings when compiled
with W=1:

Node /soc/eccmgr@ffd08140 has a unit name, but no reg property
Node /soc/usbphy@0 has a unit name, but no reg property

Remove the superfluous unit names.

Signed-off-by: Florian Vaussard <florian.vaussard@heig-vd.ch>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>