brcm: Link CM4's WiFi firmware with DMI machine name.

The kernel when booted in ACPI mode with SMBIOS/DMI
data uses the DMI data to set the machine
manufacture/model.

The WiFi driver uses the machine string to select the
correct firmware image. Because of this, an additional
link to select the correct firmware is needed.

Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Peter Robinson <pbrobinson@gmail.com>
Cc: Josh Boyer <jwboyer@kernel.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

WHENCE

@@ -2775,6 +2775,7 @@ File: "brcm/brcmfmac43455-sdio.raspberrypi,3-model-b-plus.txt"
 Link: brcm/brcmfmac43455-sdio.raspberrypi,3-model-a-plus.txt -> brcmfmac43455-sdio.raspberrypi,3-model-b-plus.txt
 File: "brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.txt"
 Link: brcm/brcmfmac43455-sdio.Raspberry\ Pi\ Foundation-Raspberry\ Pi\ 4\ Model\ B.txt -> brcmfmac43455-sdio.raspberrypi,4-model-b.txt
+Link: brcm/brcmfmac43455-sdio.Raspberry\ Pi\ Foundation-Raspberry\ Pi\ Compute\ Module\ 4.txt -> brcmfmac43455-sdio.raspberrypi,4-model-b.txt
 File: "brcm/brcmfmac43455-sdio.MINIX-NEO Z83-4.txt"
 File: "brcm/brcmfmac4356-pcie.gpd-win-pocket.txt"
 File: brcm/brcmfmac4356-sdio.vamrs,rock960.txt