mwifiex: do not print dot when downloading FW

Printing about 3000 lines like this

[   20.691850] mwifiex_pcie 0000:02:00.0: .
[   20.693466] mwifiex_pcie 0000:02:00.0: .

is not useful. If FW downloading will be interrupted, we will get
proper error message about that.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>