x86/platform/intel-mid: Remove unused definitions from intel-mid.h

After a few rounds of removal and refactoring Intel MID related code
some artifacts are left untouched. However, they are not used anywhere.
Remove them.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20230216193958.2971-1-andriy.shevchenko%40linux.intel.com