drivers: ethernet: phy: microchip_t1s: fix missing MDIO bus enable/disable

Call mdio_bus_enable() and mdio_bus_disable() during clause 22 register
read/write operations. Previously, these APIs were not invoked, which
could lead to improper MDIO bus handling.

This issue was observed during testing with the evb-lan8670-rmii
(an external LAN8670 PHY) connected to the SAME54 Curiosity Ultra
platform.

Signed-off-by: Parthiban Veerasooran <parthiban.veerasooran@microchip.com>