libata: make gtf_filter per-dev

Add ->gtf_filter to ata_device and set it to ata_acpi_gtf_filter when
initializing ata_link.  This is to allow quirks which apply different
gtf filters.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index aa52794..8769864 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -598,6 +598,7 @@
 #ifdef CONFIG_ATA_ACPI
 	acpi_handle		acpi_handle;
 	union acpi_object	*gtf_cache;
+	unsigned int		gtf_filter;
 #endif
 	/* n_sector is CLEAR_BEGIN, read comment above CLEAR_BEGIN */
 	u64			n_sectors;	/* size of device, if ATA */