classes/kernel: move module postinst commands to kernel-base

Since kernel-base is the package that contains the files that depmod
needs to run, we should be running depmod from the kernel-base
postinstall rather than kernel-image.

Fixes [YOCTO #5392].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
classes/image: ignore modules.* changing during multilib image construction

Since we now run depmod when building images (as the postinst that does
this is now on kernel-base instead of kernel-image) it is possible to
have module file differences between the two halves of the multilib image,
and the code that checks for such differences detects this and fails.
Whitelist this file to avoid the failure.

Specifically, modules.alias, modules.dep and modules.symbol can differ
along with their .bin counterparts.

Related to fix for [YOCTO #5392].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>