kmod: needs to autoreconf

Fixes:
http://autobuild.buildroot.net/results/7a7/7a70b179f17070d0a0883f71c60030dd7d8a9102/


Didn't see widespread failure because it autoreconfed on its own just
fine if autotools infra was already present.
And didn't work before the automake patch with AUTORECONF=YES because of
an older gtk-doc.m4

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Tested-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>