compat: autoconf.h moved from linux/ to generated/ with kernel 2.6.33

compat: autoconf.h moved from linux/ to generated/ with kernel 2.6.33

Changed the headers, because autoconf.h moved from linux/ into
generated/

All compat-2.6.XX.h files are included by compat-2.6.h, so only
compat-2.6.h needs to include autoconf.h. There is no situation known to
me where you want to include any compat-2.6.XX.h file directly.

This fixes build with kernel 2.6.33, without it complains about a
missing import:
/include/linux/compat-2.6.h:4:28: error: linux/autoconf.h: No such file or directory

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>