kernel-arch: add macro-prefix-map in KERNEL_CC

kernel-arch: add macro-prefix-map in KERNEL_CC

When building external modules, macros can include absolute names of
kernel headers. The macro-prefix-map for the STAGING_KERNEL_DIR is
currently missing. Add it in the same way as its done in bitbake.conf.

This fixes reproducible builds and following build error:
ERROR: cryptodev-module-1.14-r0 do_package_qa: QA Issue: File <..>
cryptodev.ko <..> contains reference to TMPDIR [buildpaths]

Signed-off-by: Stefan Müller-Klieser <s.mueller-klieser@phytec.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>