libata-acpi: adjust constness in ata_acpi_gtm/stm() parameters

* No internal function uses const ata_port. Drop const from @ap.

* Make ata_acpi_stm() copy @stm before using it and change @stm to
const.

Signed-off-by: Tejun Heo <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/ata/libata-acpi.c

···
  * RETURNS:
  * 0 on success, -ENOENT if _GTM doesn't exist, -errno on failure.
  */
-int ata_acpi_gtm(const struct ata_port *ap, struct ata_acpi_gtm *gtm)
+int ata_acpi_gtm(struct ata_port *ap, struct ata_acpi_gtm *gtm)
 {
 	struct acpi_buffer output = { .length = ACPI_ALLOCATE_BUFFER };
 	union acpi_object *out_obj;
···
  * RETURNS:
  * 0 on success, -ENOENT if _STM doesn't exist, -errno on failure.
  */
-int ata_acpi_stm(const struct ata_port *ap, struct ata_acpi_gtm *stm)
+int ata_acpi_stm(struct ata_port *ap, const struct ata_acpi_gtm *stm)
 {
 	acpi_status status;
+	struct ata_acpi_gtm		stm_buf = *stm;
 	struct acpi_object_list         input;
 	union acpi_object               in_params[3];
 
 	in_params[0].type = ACPI_TYPE_BUFFER;
 	in_params[0].buffer.length = sizeof(struct ata_acpi_gtm);
-	in_params[0].buffer.pointer = (u8 *)stm;
+	in_params[0].buffer.pointer = (u8 *)&stm_buf;
 	/* Buffers for id may need byteswapping ? */
 	in_params[1].type = ACPI_TYPE_BUFFER;
 	in_params[1].buffer.length = 512;

include/linux/libata.h

···
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI
 extern int ata_acpi_cbl_80wire(struct ata_port *ap);
-int ata_acpi_stm(const struct ata_port *ap, struct ata_acpi_gtm *stm);
-int ata_acpi_gtm(const struct ata_port *ap, struct ata_acpi_gtm *stm);
+int ata_acpi_stm(struct ata_port *ap, const struct ata_acpi_gtm *stm);
+int ata_acpi_gtm(struct ata_port *ap, struct ata_acpi_gtm *stm);
 #else
 static inline int ata_acpi_cbl_80wire(struct ata_port *ap) { return 0; }
 #endif