drm/hyperv: Fix an error handling path in hyperv_vmbus_probe()

drm/hyperv: Fix an error handling path in hyperv_vmbus_probe()

hyperv_setup_vram() calls vmbus_allocate_mmio(). This must be undone in
the error handling path of the probe, as already done in the remove
function.

Fixes: a0ab5abced55 ("drm/hyperv : Removing the restruction of VRAM allocation with PCI bar size")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/7dfa372af3e35fbb1d6f157183dfef2e4512d3be.1659297696.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Wei Liu <wei.liu@kernel.org>