Fix for Yocto deprecation issue on MIT license file.
WARNING: initscripts-swupdate-1.0-r0 do_populate_lic:
${COREBASE}/LICENSE is not a valid license file, please use
'${COMMON_LICENSE_DIR}/MIT' for a MIT License file in LIC_FILES_CHKSUM.
Signed-off-by: Jan Vermaete <jan.vermaete@gmail.com>