mwifiex: drop num CPU notice

This print isn't very useful. It's also different between
mwifiex_add_card() and mwifiex_reinit_sw(), and I'd like to consolidate
them eventually.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>