Fix conflicts when "usrmerge" is in DISTRO_FEATURE

FILES_ are not set correct and conflict when "usrmerge"
is set in DISTRO_FEATURES. Do not use it and relay on the
automatic rules in Yocto (headers are automatic put in -dev
and static libraries in -staticdev).

Signed-off-by: Stefano Babic <sbabic@denx.de>

recipes-support/swupdate/swupdate.inc

@@ -20,9 +20,6 @@ INSANE_SKIP_${PN} = "ldflags"
 PACKAGES =+ "${PN}-www"
 
 FILES_${PN}-www = "/www/*"
-FILES_${PN}-dev = "${includedir}"
-FILES_${PN}-staticdev = "${libdir}"
-FILES_${PN} = "${bindir}/* ${sysconfdir}"
 
 S = "${WORKDIR}/git/"