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/M5235EVB_Flash32_defconfig b/configs/M5235EVB_Flash32_defconfig
index dfdf136..9812eae 100644
--- a/configs/M5235EVB_Flash32_defconfig
+++ b/configs/M5235EVB_Flash32_defconfig
@@ -23,6 +23,10 @@
 CONFIG_ENV_ADDR=0xFFE04000
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SYS_I2C_LEGACY=y
+CONFIG_SYS_I2C_FSL=y
+CONFIG_SYS_FSL_I2C_OFFSET=0x300
+CONFIG_SYS_I2C_SLAVE=0x7F
+CONFIG_SYS_I2C_SPEED=80000
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_SYS_FLASH_PROTECTION=y