[POWERPC] fsl: Update fsl_soc to use cell-index property of I2C nodes

Currently, fsl_i2c_of_init() uses the order of the I2C adapter nodes in the
device tree to enumerate the I2C adapters.  Instead, let's check for the
cell-index property and use it if it exists.

This is handy for device drivers that need to identify the I2C adapters by
specific numbers.  The Freescale MPC8610 ASoC V2 sound drivers are an example.
Signed-off-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

arch/powerpc/sysdev/fsl_soc.c

@@ -496,6 +496,8 @@ static int __init fsl_i2c_of_init(void)
 		struct resource r[2];
 		struct fsl_i2c_platform_data i2c_data;
 		const unsigned char *flags = NULL;
+		int idx;
+		const u32 *iprop;
 
 		memset(&r, 0, sizeof(r));
 		memset(&i2c_data, 0, sizeof(i2c_data));
@@ -506,7 +508,10 @@ static int __init fsl_i2c_of_init(void)
 
 		of_irq_to_resource(np, 0, &r[1]);
 
-		i2c_dev = platform_device_register_simple("fsl-i2c", i, r, 2);
+		iprop = of_get_property(np, "cell-index", NULL);
+		idx = iprop ? *iprop : i;
+
+		i2c_dev = platform_device_register_simple("fsl-i2c", idx, r, 2);
 		if (IS_ERR(i2c_dev)) {
 			ret = PTR_ERR(i2c_dev);
 			goto err;
@@ -528,7 +533,8 @@ static int __init fsl_i2c_of_init(void)
 		if (ret)
 			goto unreg;
 
-		of_register_i2c_devices(np, i++);
+		of_register_i2c_devices(np, idx);
+		i++;
 	}
 
 	return 0;