qextserialport: add license file

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/qextserialport/qextserialport.mk

@@ -9,6 +9,7 @@ QEXTSERIALPORT_SITE = https://qextserialport.googlecode.com/git
 QEXTSERIALPORT_SITE_METHOD = git
 
 QEXTSERIALPORT_LICENSE = MIT
+QEXTSERIALPORT_LICENSE_FILES = LICENSE
 
 QEXTSERIALPORT_INSTALL_STAGING = YES