wifi: mwifiex: remove unnecessary checks for valid priv

The pointers in adapter->priv[] are allocated in mwifiex_register().
With an allocation failed the function will return an error and
driver initialization is aborted. This makes all checks for valid
priv pointers unnecessary throughout the driver. In many places
the pointers are assumed to be valid without checks, this patch
removes the remaining checks.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20240816-mwifiex-remove-priv-checks-v1-1-6dd6553e8ed9@pengutronix.de