wifi: ath11k: remove MHI LOOPBACK channels

There is no driver to match these two channels, so
remove them. This fixes warnings from MHI subsystem during suspend:

mhi mhi0_LOOPBACK: 1: Failed to reset channel, still resetting
mhi mhi0_LOOPBACK: 0: Failed to reset channel, still resetting

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30

Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Link: https://msgid.link/20240221024725.10057-3-quic_bqiang@quicinc.com