acpi: Provide ia64 dummy implementation of acpi_proc_quirk_mwait_check()

Commit 0a0e2ea642f6 ("ACPI: processor: Move MWAIT quirk out of
acpi_processor.c") moved the MWAIT quirk code into arch/x86 but left
calls to it in the ACPI PDC processor code that is shared with Itanium,
breaking the latter build.

Since the quirk is specific to a certain x86-based platform, stub out
the function acpi_proc_quirk_mwait_check() when building for ia64.

Fixes: 0a0e2ea642f6 ("ACPI: processor: Move MWAIT quirk out of acpi_processor.c")
Signed-off-by: Ard Biesheuvel <[e-mail]>

arch/ia64/kernel/acpi.c

···
  * TBD when IA64 starts to support suspend...
  */
 int acpi_suspend_lowlevel(void) { return 0; }
+
+void acpi_proc_quirk_mwait_check(void)
+{
+}