phy: ralink: Kconfig: enable COMPILE_TEST on mt7621-pci-phy driver

After use the clock apis and avoid custom architecture
code this driver can properly be enabled for COMPILE_TEST.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210508070930.5290-5-sergio.paracuellos@gmail.com


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