x86, config: Introduce an INTEL_MID configuration

x86, config: Introduce an INTEL_MID configuration

We need to carve up the configuration between:

 - MID general
 - Moorestown specific
 - Medfield specific
 - Future devices

As a base point create an INTEL_MID configuration property. We
make the existing MRST configuration a sub-option. This means
that the rest of the kernel config can still use X86_MRST checks
without anything going backwards.

After this is merged future patches will tidy up which devices
are MID and which are X86_MRST, as well as add options for
Medfield.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20110712164859.7642.84136.stgit@bob.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@elte.hu>