mwifiex: fix missing debug messages

Some critical messages are missed until "adapter->dev"
gets initialized in mwifiex_register_dev().
We will use pr_* print message instead of mwifiex_dbg at
those places to resolve the problem.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>