net: dsa: microchip: Add suspend/resume support to KSZ DSA driver

net: dsa: microchip: Add suspend/resume support to KSZ DSA driver

The KSZ DSA driver starts a timer to read MIB counters periodically to
avoid count overrun.  During system suspend this will give an error for
not able to write to register as the SPI system returns an error when
it is in suspend state.  This implementation stops the timer when the
system goes into suspend and restarts it when resumed.

Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20241218020311.70628-1-Tristram.Ha@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>