hps: also obey $(EXTRA_LITEX_ARGS)
hps: also obey $(EXTRA_LITEX_ARGS)

Same as PR #216.

Signed-off-by: Dan Callaghan <c6268a61d01f53ee8e097a439feb27b30b61efda@google.com>

google/CFU-Playground,google/CFU-Playground,google/CFU-Playground,google/CFU-Playground