wifi: ath12k: dp_mon: Fix uninitialized warning related to the pktlog

Uninitialized warning in the code changes related to pktlog, which is not
completely supported in ath12k driver yet. Hence, remove the changes to
avoid the warning.

Warning:
drivers/net/wireless/ath/ath12k/dp_mon.c:2138:18: warning: variable 'rx_buf_sz' is uninitialized when used here [-Wuninitialized]

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0-03171-QCAHKSWPL_SILICONZ-1
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thiraviyam Mariyappan <quic_tmariyap@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20221221105529.19345-5-quic_tmariyap@quicinc.com