drm/amdgpu: adjust sequence of ip_discovery init and timeout_setting

drm/amdgpu: adjust sequence of ip_discovery init and timeout_setting

what:
1)move timtout setting before ip_early_init to reduce exclusive mode
cost for SRIOV

2)move ip_discovery_init() to inside of amdgpu_discovery_reg_base_init()
it is a prepare for the later upcoming patches.

why:
in later upcoming patches we would use a new mailbox event --
"req_gpu_init_data", which is a callback hooked in adev->virt.ops and
this callback send a new event "REQ_GPU_INIT_DAT" to host to notify
host to do some preparation like "IP discovery/vbios on the VF FB"
and this callback must be:

A) invoked after set_ip_block() because virt.ops is configured during
set_ip_block()

B) invoked before ip_discovery_init() becausen ip_discovery_init()
need host side prepares everything in VF FB first.

current place of ip_discovery_init() is before we can invoke callback
of adev->virt.ops, thus we must move ip_discovery_init() to a place
after the adev->virt.ops all settle done, and the perfect place is in
amdgpu_discovery_reg_base_init()

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Emily Deng <Emily.Deng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>