net: ti: icssg-prueth: Add ICSSG FW Stats

The ICSSG firmware maintains set of stats called PA_STATS.
Currently the driver only dumps 4 stats. Add support for dumping more
stats.

The offset for different stats are defined as MACROs in icssg_switch_map.h
file. All the offsets are for Slice0. Slice1 offsets are slice0 + 4.
The offset calculation is taken care while reading the stats in
emac_update_hardware_stats().

The statistics are documented in
Documentation/networking/device_drivers/icssg_prueth.rst

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://patch.msgid.link/20250424095316.2643573-1-danishanwar@ti.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>