kernel-devsrc: fix usrmerge install path

kernel-devsrc: fix usrmerge install path

Update /lib to $nonarch_base_libdir to fix package QA errors when
usermerge is enabled in DISTRO_FEATURES.

ERROR: kernel-devsrc-1.0-r0 do_package_qa: QA Issue: kernel-devsrc
package is not obeying usrmerge distro feature. /lib should be relocated
to /usr. [usrmerge]

Signed-off-by: Allen Wild <allenwild93@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>