brcmfmac: restrict error condition in brcmf_inform_bss()

The function brcmf_inform_bss() validates the version received
from the device, before processing the individual bss entries.
This error condition is only applicable when the list contains
entries. A specific scan, ie. for a specific ssid, can result
in a scan completion without finding any bss entries. No need
to flag it as an error in the log when this happens.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>