scsi: hpsa: select CONFIG_SCSI_SAS_ATTR

The hpsa driver recently started using the sas transport class, but it
does not ensure that the corresponding code is actually built, which
may lead to a link error:

drivers/built-in.o: In function `hpsa_free_sas_phy':
(.text+0x1ce874): undefined reference to `sas_port_delete_phy'
(.text+0x1ce87c): undefined reference to `sas_phy_free'
drivers/built-in.o: In function `hpsa_alloc_sas_port':
(.text+0x1ceb9c): undefined reference to `sas_port_alloc_num'
(.text+0x1ceba8): undefined reference to `sas_port_add'
drivers/built-in.o: In function `hpsa_init':
(.init.text+0x8838): undefined reference to `sas_attach_transport'
(.init.text+0x8868): undefined reference to `sas_release_transport

This adds 'select SCSI_SAS_ATTR' in the Kconfig entry, just like we do
for all other drivers using those functions.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: d04e62b9 ("hpsa: add in sas transport class")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Don Brace <don.brace@pmcs.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>