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/P1020RDB-PC_36BIT_SPIFLASH_defconfig b/configs/P1020RDB-PC_36BIT_SPIFLASH_defconfig
index 4431523..d279277 100644
--- a/configs/P1020RDB-PC_36BIT_SPIFLASH_defconfig
+++ b/configs/P1020RDB-PC_36BIT_SPIFLASH_defconfig
@@ -50,6 +50,10 @@
 CONFIG_DM=y
 CONFIG_DM_I2C=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
+CONFIG_SYS_I2C_FSL=y
+CONFIG_SYS_FSL_I2C_OFFSET=0x3000
+CONFIG_SYS_FSL_HAS_I2C2_OFFSET=y
+CONFIG_SYS_FSL_I2C2_OFFSET=0x3100
 CONFIG_SYS_I2C_EEPROM_ADDR=0x52
 CONFIG_FSL_ESDHC=y
 CONFIG_MTD=y