[SCSI] add flag to skip the runtime PM calls on the host

With previous change, now the ata port runtime suspend will happen as:

disk suspend --> scsi target suspend --> scsi host suspend --> ata port
suspend

ata port(parent device) suspend need to schedule scsi EH which will resume
scsi host(child device). Then the child device resume will in turn make
parent device resume first. This is kind of recursive.

This patch adds a new flag Scsi_Host::eh_noresume.
ata port will set this flag to skip the runtime PM calls on scsi host.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 50266c9..5f7d5b3 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -669,6 +669,9 @@
 	/* Asynchronous scan in progress */
 	unsigned async_scan:1;
 
+	/* Don't resume host in EH */
+	unsigned eh_noresume:1;
+
 	/*
 	 * Optional work queue to be utilized by the transport
 	 */