Added support for Wolfson Audio Card by Element-14 on Raspberry Pi Model B

Hi All,

Last pull request where I was trying to push the support for Wolfson Audio Card , somehow got broken.

This is a fresh pull request with reference to the last pull request i.e.
 "Added support for Wolfson Audio Card by Element-14 #672 "
 
Please find the patches to support Element 14 Wolfson Audio Card.

This patch-set addresses feedback comments on the previous pull request.

The patch bundle includes the machine driver and few other supporting patches to offer the functionality of WM5102 and WM8804 codecs drivers.

The current patch-set does not support SPDIF functionality. We are working on a patch-set that will be pushed to the mainline Kernel and 
once these have been merged we will submit them for adding them into the raspberry-pi kernel.

For your reference, the following link takes you to the official product page.
http://www.element14.com/community/community/raspberry-pi/raspberry-pi-accessories/wolfson_pi?CMP=KNC-EU-RPI-ACC-Wolfson

~Manish Gupta