superio/aspeed: Remove unused aspeed include path

Working on some other code, I noticed that superio/aspeed was added as
an include path even though I wasn't using it.  I investigated and found
that NOTHING is using it.  The files in the aspeed directory all
reference files in their own directory.

The supermicro x11-lga1151-series boards are the only ones using this
SIO.

TEST=util/abuild/abuild -t supermicro/x11-lga1151-series

Signed-off-by: Martin Roth <martin@coreboot.org>
Change-Id: I377066451a50452c17c9bfaa0f815f69e039984e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37390
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/superio/aspeed/Makefile.inc b/src/superio/aspeed/Makefile.inc
index 6d0cc26..b9494fa 100644
--- a/src/superio/aspeed/Makefile.inc
+++ b/src/superio/aspeed/Makefile.inc
@@ -20,5 +20,3 @@
 
 subdirs-y += ast2400
 subdirs-y += common
-
-CPPFLAGS_common += -Isrc/superio/aspeed