ide: simplify 'struct ide_taskfile'

Make 'struct ide_taskfile' cover only 8 register values and thus put two such
fields ('tf' and 'hob') into 'struct ide_cmd', dropping unnecessary 'tf_array'
field from it.

This required changing the prototype of ide_get_lba_addr() and ide_tf_dump().

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
[bart: fix setting of ATA_LBA bit for LBA48 commands in __ide_do_rw_disk()]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>