Convert CONFIG_SYS_I2C_SOFT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_SOFT
   CONFIG_SYS_I2C_SOFT_SPEED
   CONFIG_SYS_I2C_SOFT_SLAVE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/km_kirkwood_pci_defconfig b/configs/km_kirkwood_pci_defconfig
index fb1b93d..5a49acb 100644
--- a/configs/km_kirkwood_pci_defconfig
+++ b/configs/km_kirkwood_pci_defconfig
@@ -47,6 +47,8 @@
 CONFIG_NETCONSOLE=y
 CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_BOOTCOUNT_RAM=y
+CONFIG_SYS_I2C_SOFT=y
+CONFIG_SYS_I2C_SOFT_SLAVE=0x0
 CONFIG_SYS_I2C_EEPROM_ADDR=0x50
 # CONFIG_MMC is not set
 CONFIG_MTD=y