Similarly to sas report general and discovery responses, define the
structure struct smp_rps_resp to handle SATA PHY report responses using a
structure with a size that is exactly equal to the sas defined response
size.

With this change, struct smp_resp becomes unused and is removed.

Link: https://lore.kernel.org/r/20220609022456.409087-4-damien.lemoal@opensource.wdc.comReviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>