mach-sa1100: fix PCI build problem

The PCI nanoengine driver in the SA1100 machine probably has not
been building for some time. It probably dragged hardware.h
in implicitly and now it doesn't anymore. After this an SA1100
build selecting all system variants will build successfully.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>