rtw88: avoid FW info flood

The FW info was printed everytime driver is powered on, such as
leaving IDLE state. It will flood the kernel log.

Move the FW info printing to callback when FW is loaded, so
that will only be printed once when device is probed.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>