dm flakey: correct ctr alloc failure mesg

Remove the reference to the "linear" target from the error message
issued when allocation fails in the flakey target.

Cc: Robin Dong <sanbai@taobao.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

drivers/md/dm-flakey.c

@@ -176,7 +176,7 @@ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 	if (!fc) {
-		ti->error = "Cannot allocate linear context";
+		ti->error = "Cannot allocate context";
 		return -ENOMEM;
 	}
 	fc->start_time = jiffies;