Add android.hardware.ethernet.xml for ranchu targets

This commit adds android.hardware.ethernet.xml file for ethernet
permission to PRODUCT_COPY_FILES which will be copied to
/system/etc/permission folder on the target. Reason for adding
this permission file is for enabling the ethernet and having
functional networking until RIL backend support in ranchu is
implemented.

This requires dhcpcd_eth0 service definition in init.ranchu.rc.

Architectures that use goldfish emulator do not need ethernet
support, because networking is provided by RIL.

Change-Id: I7972f80cf78c0fdecf3fde45bf018230bbcefd38