drm/amdgpu/SRIOV: Extend VF reset request wait period

In Virtualization case, when one VF is sending too many
FLR requests, hypervisor would stop responding to this
VF's request for a long period of time. This is called
event guard. During this period of cooling time, guest
driver should wait instead of doing other things. After
this period of time, guest driver would resume reset
process and return to normal.

Currently, guest driver would wait 12 seconds and return fail
if it doesn't get response from host.

Solution: extend this waiting time in guest driver and poll
response periodically. Poll happens every 6 seconds and it will
last for 60 seconds.

v2: change the max repetition times from number to macro.

Signed-off-by: Jiange Zhao <Jiange.Zhao@amd.com>
Acked-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>