wifi: brcmfmac: silence warning for non-existent, optional firmware

wifi: brcmfmac: silence warning for non-existent, optional firmware

The driver tries to load optional firmware files, specific to
the actual board compatible. These might not exist resulting in a warning
like this:
brcmfmac mmc2:0001:1: Direct firmware load for brcm/brcmfmac4373-sdio.tq,imx93-tqma9352-mba93xxla-mini.bin failed with error -2

Silence this by using firmware_request_nowait_nowarn() for all firmware
loads which use brcmf_fw_request_done_alt_path() as callback. This one
handles optional firmware files.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Tested-by: Christian Hewitt <christianshewitt@gmail.com>
[arend: use nowarn api for optional firmware files]
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20260328140121.2583606-1-arend.vanspriel@broadcom.com
[clean up code a bit]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>