net: lan969x: add function for calculating the DSM calendar

net: lan969x: add function for calculating the DSM calendar

Lan969x has support for RedBox / HSR / PRP (not implemented yet). In
order to accommodate for this in the future, we need to give lan969x it's
own function for calculating the DSM calendar.

The function calculates the calendar for each taxi bus. The calendar is
used for bandwidth allocation towards the ports attached to the taxi
bus. A calendar configuration consists of up-to 64 slots, which may be
allocated to ports or left unused. Each slot accounts for 1 clock cycle.

Also expose sparx5_cal_speed_to_value(), sparx5_get_port_cal_speed,
sparx5_cal_bw and SPX5_DSM_CAL_EMPTY for use by lan969x.

Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://patch.msgid.link/20241024-sparx5-lan969x-switch-driver-2-v2-11-a0b5fae88a0f@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>