scsi: core: Fix a procfs host directory removal regression

In the Linux kernel, the following vulnerability has been resolved: scsi: core: Fix a procfs host directory removal regression scsi_proc_hostdir_rm() decreases a reference counter and hence must only be called once per host that is removed. This change does not require a scsi_add_host_with_dma() change since scsi_add_host_with_dma() will return 0 (success) if scsi_proc_host_add() is called.