xilinx: common: Move ZYNQ_GEM_I2C_MAC_OFFSET to board Kconfig

There is no reason to have ZYNQ specific Kconfig macro in generic location
to be visible for all other SoCs. That's why move it to Xilinx common
location to be visible only for us.
Also introduce new bool entry ZYNQ_MAC_IN_EEPROM to have also an option to
disable it or enable. This has connection to code which is reading the
whole content of i2c and also work with the rest of date not just with MAC
address.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/Kconfig b/board/xilinx/Kconfig
index c80d0a8..01d7f8e 100644
--- a/board/xilinx/Kconfig
+++ b/board/xilinx/Kconfig
@@ -56,3 +56,20 @@
 	default 0x7F80000 if ARCH_VERSAL
 	help
 	   Specifies distro boot script offset in NAND/NOR flash.
+
+config ZYNQ_MAC_IN_EEPROM
+	bool "Reading MAC address from EEPROM"
+	help
+	  Enable this option if your MAC address is saved in eeprom and
+	  xlnx,eeprom DT property in chosen node points to it.
+
+if ZYNQ_MAC_IN_EEPROM
+
+config ZYNQ_GEM_I2C_MAC_OFFSET
+	hex "Set the I2C MAC offset"
+	default 0x0
+	depends on DM_I2C
+	help
+	  Set the MAC offset for i2C.
+
+endif