kbuild: do not include include/config/auto.conf from adjust_autoksyms.sh

Commit cd195bc4 ("kbuild: split adjust_autoksyms.sh in two parts")
split out the code that needs include/config/auto.conf.

This script no longer needs to include include/config/auto.conf.

Fixes: cd195bc4

 ("kbuild: split adjust_autoksyms.sh in two parts")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>