pmic_fsl: Introduce FSL_PMIC_I2C_LENGTH

Introduce FSL_PMIC_I2C_LENGTH to configure the number of bytes that are used to
communicate with the PMIC via I2C.

Instead of hardcoding the value, pass the number via a configurable option per
PMIC type.

This will be useful for adding support for PMIC MC34704 from Freescale, which
uses only one byte in its I2C protocol.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/include/configs/mx53loco.h b/include/configs/mx53loco.h
index 0658dd3..9e8f5ce 100644
--- a/include/configs/mx53loco.h
+++ b/include/configs/mx53loco.h
@@ -93,6 +93,7 @@
 #define CONFIG_PMIC_I2C
 #define CONFIG_DIALOG_PMIC
 #define CONFIG_PMIC_FSL
+#define CONFIG_PMIC_FSL_MC13892
 #define CONFIG_SYS_DIALOG_PMIC_I2C_ADDR	0x48
 #define CONFIG_SYS_FSL_PMIC_I2C_ADDR	0x8