net: ti: icssg-prueth: Fix fdb hash size configuration

net: ti: icssg-prueth: Fix fdb hash size configuration

The ICSSG driver does the initial FDB configuration which
includes setting the control registers. Other run time
management like learning is managed by the PRU's. The default
FDB hash size used by the firmware is 512 slots, which is
currently missing in the current driver. Update the driver
FDB config to include FDB hash size as well.

Please refer trm [1] 6.4.14.12.17 section on how the FDB config
register gets configured. From the table 6-1404, there is a reset
field for FDB_HAS_SIZE which is 4, meaning 1024 slots. Currently
the driver is not updating this reset value from 4(1024 slots) to
3(512 slots). This patch fixes this by updating the reset value
to 512 slots.

[1]: https://www.ti.com/lit/pdf/spruim2
Fixes: abd5576b9c57f ("net: ti: icssg-prueth: Add support for ICSSG switch firmware")
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251104104415.3110537-1-m-malladi@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>