xilinx: Remove unused ZYNQ_MAC_IN_EEPROM/ZYNQ_GEM_I2C_MAC_OFFSET entries

The commit ba74bcf3 ("xilinx: common: Remove
zynq_board_read_rom_ethaddr()") removed zynq_board_read_rom_ethaddr()
because xlnx,eeprom link via DT chosen node is no longer used. But forget
to remove Kconfig entries which are used by this code only.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/f97451ed33409838efea4071553b6da795cfc578.1669192026.git.michal.simek@amd.com