x86: Add Intel Tangier support

x86: Add Intel Tangier support

Add Intel Tangier SoC support.

Intel Tangier SoC is a core part of Intel Merrifield platform. For
example, Intel Edison board is based on such platform.

The patch is based on work done by the following people (in alphabetical
order):
	Aiden Park <[email protected]>
	Dukjoon Jeon <[email protected]>
	eric.park <[email protected]>
	Fabien Chereau <[email protected]>
	Scott D Phillips <[email protected]>
	Sebastien Colleur <[email protected]>
	Steve Sakoman <[email protected]>
	Vincent Tinelli <[email protected]>

Reviewed-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Signed-off-by: Vincent Tinelli <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>