wifi: brcmfmac: add vendor name in revinfo debugfs file

wifi: brcmfmac: add vendor name in revinfo debugfs file

Upon probe the driver determines the vendor supporting the device.
Expose this information in the revinfo debugfs file.

Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221129135446.151065-7-arend.vanspriel@broadcom.com