wifi: ath11k: Fix error path in ath11k_pcic_ext_irq_config

If one of the dummy allocation fails in ath11k_pcic_ext_irq_config(),
the previous allocated devices might leak due to returning without
deallocating the devices.

Instead of returning on the error path, deallocate all the previously
allocated net_devices and then return.

Fixes: bca592ea

 ("wifi: ath11k: allocate dummy net_device dynamically")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240508185902.70975-1-leitao@debian.org