[SCSI] Make scsi_host_template::proc_name const char * instead of char *.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
collapsed with fw-sbp2 patch "Drop cast to non-const char * in host
template initialization." from Kristian Høgsberg

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>