Pass cflags to kernel builds with `=`
Pass cflags to kernel builds with `=`

Pass extra cflags using `--extra-cflags=`, rather than a space, to avoid
argparse trying to interpret the cflags as arguments.

This was fixed for Linux in `54cfbe5 Fix --extra-cflags argument usage
in kmod_build.py call`.

Change-Id: I03e6ca5cc64e1a000c03fc7176cbac765209864d
Signed-off-by: Chris Diamand <1f58517798882095082bdee11eba81705511491e@arm.com>

ARM-software/bob-build,ARM-software/bob-build,ARM-software/bob-build,ARM-software/bob-build,ARM-software/bob-build