scsi: esas2r: Introduce scsi_template_proc_dir()

Prepare for removing the 'proc_dir' and 'present' members from the SCSI
host template. This commit does not change any functionality.

Reviewed-by: John Garry <john.garry@huawei.com>
Cc: Bradley Grove <linuxdrivers@attotech.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221015002418.30955-3-bvanassche@acm.org


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>