zephyr-kernel-src: fix build with latest dtc

dtc is now built with Meson, which changes the version string in the
--version output.  Zephyr matches this in a regular expression which now
fails, so update it to match both Make and Meson formats.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>