xilinx: common: Remove !DM_i2C code for reading mac from eeprom

All platforms are converted to DM_I2C that's why there is no reason to
keep this code here.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 704c8dd..d6e677f 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -245,6 +245,7 @@
 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.