km/ppc: migrate all mpc83xx to DM_I2C

Enable DM_I2C and I2C mux to get rid of the usage of the legacy
i2c driver.

Signed-off-by: Holger Brunck <holger.brunck@hitachienergy.com>
diff --git a/board/keymile/Kconfig b/board/keymile/Kconfig
index cd8a06e..e5d7c80 100644
--- a/board/keymile/Kconfig
+++ b/board/keymile/Kconfig
@@ -100,8 +100,7 @@
 config KM_IVM_BUS
 	int "IVM I2C Bus"
 	default 0 if ARCH_SOCFPGA
-	default 1 if MPC85xx || ARCH_LS1021A
-	default 2 if MPC83xx
+	default 1 if PPC || ARCH_LS1021A
 	help
 	  Identifier number of I2C bus, where the inventory EEPROM is connected to.