makefile: Get rid of unneeded include prepends

We no longer need these since enum include handling was fixed in sdbus++
by sdbusplus@8515eae7adcb9811ba271d05d82f66d48b1df082

Change-Id: I8b95157d573216eadb8a0e18e19294182b2be222
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed