greybus: kernel_ver.h: add a ' ' character to KERNEL_VERSION()

You should always put a space after a ',', so do it for the
KERNEL_VERSION() macro as well.  This makes checkpatch.pl happy also.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>