Add the programming sequence.

v2:
Change donwload wait loop to more efficient.
Move C2PMSG_CMD_GFX_USB_PD_FW_VER defintion

v3: Fix lack of loop counter increment typo

v4: Remove superflous status reg read
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>