ptp: netc: add periodic pulse output support

ptp: netc: add periodic pulse output support

NETC Timer has three pulse channels, all of which support periodic pulse
output. Bind the channel to a ALARM register and then sets a future time
into the ALARM register. When the current time is greater than the ALARM
value, the FIPER register will be triggered to count down, and when the
count reaches 0, the pulse will be triggered. The PPS signal is also
implemented in this way.

i.MX95 only has ALARM1 can be used as an indication to the FIPER start
down counting, but i.MX943 has ALARM1 and ALARM2 can be used. Therefore,
only one channel can work for i.MX95, two channels for i.MX943 as most.

In addition, change the PPS channel to be dynamically selected from fixed
number (0) because add PTP_CLK_REQ_PEROUT support.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250829050615.1247468-7-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>