ASoC: SOF: add a pointer to download repo in case FW request fails

ASoC: SOF: add a pointer to download repo in case FW request fails

The SOF firmware and topology files are not distributed via
linux-firmware. To help debugging cases where correct firmware is
not installed, print a pointer to the official upstream repository
for Sound Open Firmware releases.

BugLink: https://github.com/thesofproject/sof/issues/3665
Reported-by: Bruce Perens <bruce@perens.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Marc Herbert <marc.herbert@intel.com>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Link: https://lore.kernel.org/r/20210127122358.1014458-1-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>