ACPICA: Miscellaneous lint changes

Unused variables/headers, casting, etc.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/tbinstal.c b/drivers/acpi/acpica/tbinstal.c
index f865d5a..63e8232 100644
--- a/drivers/acpi/acpica/tbinstal.c
+++ b/drivers/acpi/acpica/tbinstal.c
@@ -472,7 +472,7 @@
 	 * lock may block, and also since the execution of a namespace walk
 	 * must be allowed to use the interpreter.
 	 */
-	acpi_ut_release_mutex(ACPI_MTX_INTERPRETER);
+	(void)acpi_ut_release_mutex(ACPI_MTX_INTERPRETER);
 	status = acpi_ut_acquire_write_lock(&acpi_gbl_namespace_rw_lock);
 
 	acpi_ns_delete_namespace_by_owner(owner_id);