chromebook snow: remove $(HOST_DIR)/usr reference from README

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

board/chromebook/snow/readme.txt

@@ -88,7 +88,7 @@ you will probably want the rootfs to occupy the whole remaining space.
 
 cgpt may be used to check current layout:
 
-	output/host/usr/bin/cgpt show $SD
+	output/host/bin/cgpt show $SD
 
 All sizes and all offsets are in 512-byte blocks.