wifi: atk10k: Don't opencode ath10k_pci_priv() in ath10k_ahb_priv()

This introduces no changes in the compiled result (tested for an
ARCH=arm allmodconfig build).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230601082556.2738446-5-u.kleine-koenig@pengutronix.de