ACPICA: hw: Don't carry spinlock over suspend

ACPI uses acpi_get_register() in order to get into suspend.
This function is guarded by acpi_gbl_hardware_lock, which will be carried
into resume phase.
At resume interrupts are enabled and first ACPI interrupt deadlocks on this
lock.
Solution seems to be to not lock register read, as there are no concurrent
activity at this point.

Reference: http://bugzilla.kernel.org/show_bug.cgi?id=7499

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

include/acpi/acpixf.h

@@ -314,6 +314,8 @@ acpi_resource_to_address64(struct acpi_resource *resource,
  */
 acpi_status acpi_get_register(u32 register_id, u32 * return_value);
 
+acpi_status acpi_get_register_unlocked(u32 register_id, u32 *return_value);
+
 acpi_status acpi_set_register(u32 register_id, u32 value);
 
 acpi_status