wifi: ath11k: fix the stack frame size warning in ath11k_vif_wow_set_wakeups

Fix the following W=1 kernel build warning:

drivers/net/wireless/ath/ath11k/wow.c: In function ‘ath11k_vif_wow_set_wakeups’:
drivers/net/wireless/ath/ath11k/wow.c:461:1: warning: the frame size of 1352 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Remove the nonessential variable 'struct cfg80211_pkt_pattern
old_pattern' by relocating bitmask to bytemask conversion into
ath11k_wow_convert_8023_to_80211().

Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-04358-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1

Signed-off-by: Miaoqing Pan <quic_miaoqing@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240829075253.657667-1-quic_miaoqing@quicinc.com