Convert CONFIG_SYS_IMMR to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_IMMR

We do this by consolidating the SYS_IMMR options we have and providing
defaults.

We also, in the few places where M68K was also sharing code with these
platforms, define it within the file to CONFIG_SYS_MBAR to match usage.
This should be cleaned up longer term.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
index eafd801..9a3c824 100644
--- a/drivers/i2c/fsl_i2c.c
+++ b/drivers/i2c/fsl_i2c.c
@@ -40,6 +40,10 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#ifdef CONFIG_M68K
+#define CONFIG_SYS_IMMR		CONFIG_SYS_MBAR
+#endif
+
 #if !CONFIG_IS_ENABLED(DM_I2C)
 static const struct fsl_i2c_base *i2c_base[4] = {
 	(struct fsl_i2c_base *)(CONFIG_SYS_IMMR + CONFIG_SYS_FSL_I2C_OFFSET),