i2c: fsl_i2c: Migrate to Kconfig

- As there are no boards that use different values for speed / slave on
  different buses, use a single option.
- Switch to using the common SYS_I2C_SPEED / SYS_I2C_SLAVE options.
- Introduce _HAS_ options for additional buses as only the first one is
  common to all users.
- Convert all remaining symbols to Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ids8313_defconfig b/configs/ids8313_defconfig
index d858d87..91ce5ea 100644
--- a/configs/ids8313_defconfig
+++ b/configs/ids8313_defconfig
@@ -155,6 +155,10 @@
 CONFIG_BOOTCOUNT_LIMIT=y
 CONFIG_BOOTCOUNT_I2C=y
 CONFIG_SYS_I2C_LEGACY=y
+CONFIG_SYS_I2C_FSL=y
+CONFIG_SYS_FSL_I2C_OFFSET=0x3100
+CONFIG_SYS_I2C_SLAVE=0x7F
+CONFIG_SYS_I2C_SPEED=400000
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_NOR_FLASH=y