kernel.bbclass: fix external module building
kernel.bbclass: fix external module building

Without that fix we have the following while compiling compat-wireless.
  include/linux/mmzone.h:18:30: fatal error: generated/bounds.h: No such file or directory

Note that the compat-wireless recipe will be added in another commit.

Signed-off-by: Denis 'GNUtoo' Carikli <dc53f704238ac18d4170dcdce16b661f43d75df3@no-log.org>
Signed-off-by: Koen Kooi <42e3d96910f922bdd7dd1805fe3f8aff634f391d@dominion.thruhere.net>

WindRiver-OpenSourceLabs/meta-oe-subset,WindRiver-OpenSourceLabs/meta-oe-subset