ACPI: delete acpi_os_free(), use kfree() directly

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/arch/ia64/kernel/acpi-ext.c b/arch/ia64/kernel/acpi-ext.c
index fff8292..ccd0165 100644
--- a/arch/ia64/kernel/acpi-ext.c
+++ b/arch/ia64/kernel/acpi-ext.c
@@ -51,7 +51,7 @@
 	memcpy(length, vendor->byte_data + 8, sizeof(*length));
 
   exit:
-	acpi_os_free(buffer.pointer);
+	kfree(buffer.pointer);
 	return status;
 }