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/snapper9260_defconfig b/configs/snapper9260_defconfig
index f9cc1a6..0acb95f 100644
--- a/configs/snapper9260_defconfig
+++ b/configs/snapper9260_defconfig
@@ -33,6 +33,8 @@
 CONFIG_TFTP_TSIZE=y
 CONFIG_AT91_GPIO=y
 CONFIG_CMD_PCA953X=y
+CONFIG_SYS_I2C_SOFT=y
+CONFIG_SYS_I2C_SOFT_SLAVE=0x7F
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y