net: phy: mxl-86110: Add power management and soft reset support

net: phy: mxl-86110: Add power management and soft reset support

Implement soft_reset, suspend, and resume callbacks using
genphy_soft_reset(), genphy_suspend(), and genphy_resume()
to fix PHY initialization and power management issues.

The soft_reset callback is needed to properly recover the PHY after an
ifconfig down/up cycle. Without it, the PHY can remain in power-down
state, causing MDIO register access failures during config_init().
The soft reset ensures the PHY is operational before configuration.

The suspend/resume callbacks enable proper power management during
system suspend/resume cycles.

Fixes: b2908a989c59 ("net: phy: add driver for MaxLinear MxL86110 PHY")
Signed-off-by: Stefano Radaelli <stefano.r@variscite.com>
Link: https://patch.msgid.link/20251223120940.407195-1-stefano.r@variscite.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>