ide-acpi: cleanup do_drive_get_GTF()

* ide_noacpi is already checked by ide_acpi_exec_tfs()
  which is the only user of do_drive_get_GTF().

* ide_acpi_exec_tfs() prints sufficient debug info about the
  device so no need to have excessive data about port/host.

* It is sufficient to check for drive->acpidata->obj_handle
  as it will be NULL if dev == NULL or hwif->acpidata == NULL
  or device is not present.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>