Properly filter paths to locate device directories

A device name matches when there are exactly two slashes,
and the original cod was looking for at least two slashes.

Bug: 4295425
Change-Id: Id2591a2e7b9e68dcec51cb1e33f41d2b314df98f
diff --git a/generate-blob-lists.sh b/generate-blob-lists.sh
index 6560539..eebc083 100755
--- a/generate-blob-lists.sh
+++ b/generate-blob-lists.sh
@@ -83,7 +83,7 @@
 
 for DEVICENAME in $DEVICES
 do
-  MANUFACTURERNAME=$( find device -type d | grep [^/]\*/[^/]\*/$DEVICENAME\$ | cut -f 2 -d / )
+  MANUFACTURERNAME=$( find device -type d | grep ^[^/]\*/[^/]\*/$DEVICENAME\$ | cut -f 2 -d / )
   if test $(wc -l < $ARCHIVEDIR/$DEVICENAME-without.txt) != 0 -a $(wc -l < $ARCHIVEDIR/$DEVICENAME-with.txt) != 0
   then
     (