arm64: zynqmp: Add new header file for zcu104 RevC

Created a new header file for zcu104 RevC board and added below
configurations to use MAC address from EEPROM.
	CONFIG_ZYNQ_GEM_EEPROM_ADDR
	CONFIG_ZYNQ_EEPROM_BUS
Added CONFIG_ZYNQ_GEM_I2C_MAC_OFFSET=0x20 to
xilinx_zynqmp_zcu104_revC_defconfig

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>