fsl_i2c: Added a callpoint for i2c_board_late_init

This patch adds a callpoint in i2c_init that allows board specific
i2c board initialization (typically for i2c bus reset) that is called
after i2c_init operations, allowing the i2c_board_late_init function
to use the pre-configured i2c bus speed and slave address.
diff --git a/README b/README
index 99320ab..cf6b898 100644
--- a/README
+++ b/README
@@ -1509,6 +1509,17 @@
 		custom i2c_init_board() routine in boards/xxx/board.c
 		is run early in the boot sequence.
 
+		CONFIG_SYS_I2C_BOARD_LATE_INIT
+
+		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
+		defined a custom i2c_board_late_init() routine in
+		boards/xxx/board.c is run AFTER the operations in i2c_init()
+		is completed. This callpoint can be used to unreset i2c bus
+		using CPU i2c controller register accesses for CPUs whose i2c
+		controller provide such a method. It is called at the end of
+		i2c_init() to allow i2c_init operations to setup the i2c bus
+		controller on the CPU (e.g. setting bus speed & slave address).
+
 		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
 
 		This option enables configuration of bi_iic_fast[] flags