nmhw-fwupdate: Add unbuffer tool

This tool is required to show the progress of update in real time.
Without it the output of update script is buffered and shown only at the
end of the update, letting the user not aware of what is going on.

BugzID: 62703

recipes-core/nmhw-fwupdate/nmhw-fwupdate.bb

@@ -10,6 +10,7 @@ RDEPENDS_${PN} = " \
               wget \
               bash \
               coreutils \
+              expect \
                 "
 
 SRC_URI =  " \