[SCSI] fix /proc memory leak in the SCSI core

The SCSI core calls scsi_proc_hostdir_add() from within
scsi_host_alloc(), but the corresponding scsi_proc_hostdir_rm()
routine is called from within scsi_remove_host().  As a result, if a
host is allocated and then deallocated without ever being registered,
the host's directory in /proc is leaked.

This patch (as1181b) fixes this bug in the SCSI core by moving
scsi_proc_hostdir_rm() into scsi_host_dev_release().

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>