wifi: ath12k: use correct MAX_RADIOS

The current value of the MAX_RADIOS definition is 3. This is incorrect
because no device supports more than 2 radios.

An incorrect MAX_RADIOS value can lead to:
 - unnecessary memory allocation for pdev related entities.
 - invalid pdev id validation.
 - Misconceptions for code readers.

Therefore, modify the MAX_RADIOS definition as 2.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20240514063412.3483723-3-quic_periyasa@quicinc.com