wifi: brcmfmac: keep power during suspend if board requires it

After commit 92cadedd ("brcmfmac: Avoid keeping power to SDIO card
unless WOWL is used"), the wifi adapter by default is turned off on
suspend and then re-probed on resume.

This conflicts with some embedded boards that require to remain powered.
They will fail on resume with:

brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout
ieee80211 phy1: brcmf_bus_started: failed: -110
ieee80211 phy1: brcmf_attach: dongle is not responding: err=-110
brcmfmac: brcmf_sdio_firmware_callback: brcmf_attach failed

This commit checks for the Device Tree property 'cap-power-off-cards'.
If this property is not set, it means that we do not have the capability
to power off and should therefore remain powered.

Signed-off-by: Matthias Proske <email@matthias-proske.de>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20250212185941.146958-2-email@matthias-proske.de


Signed-off-by: Johannes Berg <johannes.berg@intel.com>