net: ti: icssg-prueth: Add support for PA Stats

net: ti: icssg-prueth: Add support for PA Stats

Add support for dumping PA stats registers via ethtool.
Firmware maintained stats are stored at PA Stats registers.
Also modify emac_get_strings() API to use ethtool_puts().

This commit also maintains consistency between miig_stats and pa_stats by
- renaming the array icssg_all_stats to icssg_all_miig_stats
- renaming the structure icssg_stats to icssg_miig_stats
- renaming ICSSG_STATS() to ICSSG_MIIG_STATS()
- changing order of stats related data structures and arrays so that data
  structures of a certain stats type is clubbed together.

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://patch.msgid.link/20240822122652.1071801-3-danishanwar@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>