x86: tangier: Make _CRS for BTH0 Serialized to avoid warning

ASL compiler warns:

  ASL     board/intel/edison/dsdt.asl
  board/intel/edison/dsdt.asl.tmp    238:             Method (_CRS, 0, NotSerialized)
  Remark   2120 -      Control Method should be made Serialized ^  (due to creation of named objects within)

Do as suggested by ASL compiler.

Fixes: 5d8c4ebd ("x86: tangier: Add Bluetooth to ACPI table")
Reported-by: Ferry Toth <fntoth@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>