linux-imx-headers: whitelist version.h header
As some recipes, like imx-vpu-hantro, need to know the imx kernel
version instead of the toolchain header version.
As an example, Honister toolchain uses 5.14 kernel headers. In that
case, imx-vpu-hantro believes it needs to use dmabuf allocation
mechanism although this latter will only be enabled in upcoming NXP
kernel 5.15.
Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
(cherry picked from commit
a1c7e7bb6b141c81f8430087d236eab1e0dbb428)
