efl.bbclass: don't remove STAGING_LIBDIR STAGING_INCDIR from efl pkgconfig files

* but replace those with ${libdir} and ${includedir}
* it was breaking edbus:
  Cflags: -I${includedir}/e_dbus-1 -I/OE/shr-core/tmp-eglibc/sysroots/qemuarm/usr/include/dbus-1.0 -I/OE/shr-core/tmp-eglibc/sysroots/qemuarm/usr/lib/dbus-1.0/include
  after make install:
  Cflags: -I${includedir}/e_dbus-1 /dbus-1.0 -I/OE/shr-core/tmp-eglibc/sysroots/qemuarm/usr/lib/dbus-1.0/include
* and notice that dbus-1 is using -I{libdir} here, so replace it too

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>