wifi: ath11k: suppress add interface error

In the VIF (other than monitor type) creation request, we should not
throw the error code when the monitor VIF creation fails, since the
actual VIF creation succeeds. If we throw the error code from driver
then the actual VIF creation get fail. So suppress the monitor VIF
creation error by throwing warning message instead of error code.

Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.6.0.1-00760-QCAHKSWPL_SILICONZ-1

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20221006005842.8599-1-quic_periyasa@quicinc.com