Now that all the PHY drivers have been migrated to directly implement
the generic .handle_interrupt() callback for a seamless support of
shared IRQs and all the .config_inter() implementations clear any
pending interrupts, we can safely remove the two callbacks.

With this patch, phylib has a proper support for shared IRQs (and not
just for multi-PHY devices. A PHY driver must implement both the
.handle_interrupt() and .config_intr() callbacks for the IRQs to be
actually used.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>