staging: mt7621-pci-phy: remove driver from staging

Remove this driver from staging because it has been moved
into its properly place in the kernel.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20201121155037.21354-5-sergio.paracuellos@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>