Convert CONFIG_I2C_SET_DEFAULT_BUS_NUM et al to Kconfig

This converts the following to Kconfig:
   CONFIG_I2C_SET_DEFAULT_BUS_NUM
   CONFIG_I2C_DEFAULT_BUS_NUMBER

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P1020RDB-PC_36BIT_defconfig b/configs/P1020RDB-PC_36BIT_defconfig
index d350ff8..a77af48 100644
--- a/configs/P1020RDB-PC_36BIT_defconfig
+++ b/configs/P1020RDB-PC_36BIT_defconfig
@@ -37,6 +37,7 @@
 CONFIG_DM=y
 CONFIG_DM_I2C=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
+CONFIG_I2C_SET_DEFAULT_BUS_NUM=y
 CONFIG_SYS_I2C_FSL=y
 CONFIG_SYS_FSL_I2C_OFFSET=0x3000
 CONFIG_SYS_FSL_HAS_I2C2_OFFSET=y