wifi: ath11k: refactor ath11k_core_suspend/_resume()

wifi: ath11k: refactor ath11k_core_suspend/_resume()

Due to [1] we currently put WLAN target into WoWLAN mode regardless of
machine models. In upcoming patches we will support another mode, and
finally which mode is chosen depends on the exact machine model.

To prepare for such change, refactor the actual WoWLAN stuff in
ath11k_core_suspend() into a new helper ath11k_core_suspend_wow(), this
increase the code readability when the new suspend mode is added in
upcoming patches.

Same change applies to ath11k_core_resume();

[1] https://bugzilla.kernel.org/show_bug.cgi?id=219196

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

Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Link: https://patch.msgid.link/20250328-ath11k-bring-hibernation-back-v3-3-23405ae23431@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>