[SCSI] Log thin provisioning threshold event

At least log the message that we received a THIN PROVISIONING SOFT
THRESHOLD REACHED Unit Attention.  Also added it to unit attention
decodes.

Signed-off-by: Shyam Iyer <shyam_iyer@dell.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
index d0c8234..60d2ef2 100644
--- a/drivers/scsi/constants.c
+++ b/drivers/scsi/constants.c
@@ -772,6 +772,7 @@
 	{0x3802, "Esn - power management class event"},
 	{0x3804, "Esn - media class event"},
 	{0x3806, "Esn - device busy class event"},
+	{0x3807, "Thin Provisioning soft threshold reached"},
 
 	{0x3900, "Saving parameters not supported"},