AMD dGPUs have integrated FW that runs as soon as the
device gets power and initializes the board (determines
the amount of memory, provides configuration details to
the driver, etc.).  For direct PCIe attached cards this
happens as soon as power is applied and normally completes
well before the OS has even started loading.  However, with
hotpluggable ports like USB4, the driver needs to wait for
this to complete before initializing the device.

This normally takes 60-100ms, but could take longer on
some older boards periodically due to memory training.

Retry for up to a second.  In the non-hotplug case, there
should be no change in behavior and this should complete
on the first try.

v2: adjust test criteria
v3: adjust checks for the masks, only enable on removable devices
v4: skip bif_fb_en check

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2925Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org