Revert "serial: 8250: Let serial core initialise spin lock"

Revert "serial: 8250: Let serial core initialise spin lock"

This reverts commit c121aef7f1703f6bd3e707bab789f857a0e2d535.

It appears that in QEmu the lock has been initialised differently
(it wasn't obvious on real hardware during testing). Let's
revert the change until the better approach will be developed.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200802111612.36189-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>