On a Radxa Rock2 board with a Ampak AP6335 (Broadcom 4339 core) it seems
the card responds very quickly most of the time, unfortunately during
initialisation it sometimes seems to take just a bit over 2 seconds to
respond.

This results intialization failing with message like:
  brcmf_c_preinit_dcmds: Retreiving cur_etheraddr failed, -52
  brcmf_bus_start: failed: -52
  brcmf_sdio_firmware_callback: dongle is not responding

Increasing the timeout to allow for a bit more headroom allows the
card to initialize reliably.

A quick search online after diagnosing/fixing this showed that Google
has a similar patch in their ChromeOS tree, so this doesn't seem
specific to the board I'm using.
Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Acked-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>