pciutils: cleanup

It makes no sense to have variables that are only used in one place
(PCIUTILS_MAKE_OPTS) for different build conditions.
Just make them add-up to MAKE_OPTS and move the fixed definition up.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>