pointercal-xinput: generalize using platform family

https://jira.digi.com/browse/DEL-1105

Signed-off-by: Javier Viguera <javier.viguera@digi.com>

meta-digi-dey/recipes-graphics/xinput-calibrator/pointercal-xinput_0.0.bbappend

@@ -1,3 +1,3 @@
 # Copyright (C) 2013 Digi International.
 
-FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}/${MACHINE}/${PREFERRED_VERSION_linux-dey}:${THISDIR}/${PN}/${MACHINE}:"
+FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}/${PREFERRED_VERSION_linux-dey}:"