x11r7: fix indentation

Fixup the indentation when including the X.org server Config.in to
match all the other inclusions in x11r7/Config.in.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>