[aon_timer] Watchdog seems to be running at the wrong frequency on CW310

Description

While debugging the //sw/device/silicon_creator/rom/e2e:shutdown_watchdog_dev_400000_cw310_rom_with_fake_keys, I observe that the watchdog count does not seem to be running at 200kHz which is what the documentation claims.

I instrumented the test to pet the watchdog then wait one second and then output the count. This is the output

[2023-10-03T15:44:31.238Z  console]ROM:0c8e382c
[2023-10-03T15:44:31.238Z  console]bootstrap:1
[2023-10-03T15:44:31.238Z  console]ROM:0c8e382c
[2023-10-03T15:44:31.543Z  console]I00000 ottf_main.c:154] Running sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:32.550Z  console]I00001 hang_test.c:24] Returning after 1 seconds
[2023-10-03T15:44:32.554Z  console]I00002 hang_test.c:27] watchdog count: 251132
[2023-10-03T15:44:32.558Z  console]I00003 ottf_main.c:109] Finished sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:32.566Z  console]I00004 status.c:28] PASS!
[2023-10-03T15:44:33.161Z  console]ROM:0c8e382c
[2023-10-03T15:44:33.563Z  console]I00000 ottf_main.c:154] Running sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:34.570Z  console]I00001 hang_test.c:24] Returning after 1 seconds
[2023-10-03T15:44:34.579Z  console]I00002 hang_test.c:27] watchdog count: 251132
[2023-10-03T15:44:34.579Z  console]I00003 ottf_main.c:109] Finished sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:34.585Z  console]I00004 status.c:28] PASS!
[2023-10-03T15:44:35.181Z  console]ROM:0c8e382c
[2023-10-03T15:44:35.583Z  console]I00000 ottf_main.c:154] Running sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:36.590Z  console]I00001 hang_test.c:24] Returning after 1 seconds
[2023-10-03T15:44:36.594Z  console]I00002 hang_test.c:27] watchdog count: 251132
[2023-10-03T15:44:36.598Z  console]I00003 ottf_main.c:109] Finished sw/device/silicon_creator/rom/e2e/hang_test.c
[2023-10-03T15:44:36.605Z  console]I00004 status.c:28] PASS!

As can be seen in the log, Returning after 1 seconds is pretty almost exactly one second after the start of the test. However the timer seems to be running at 250kHz instead of 200kHz.

Start with the //sw/device/silicon_creator/rom/e2e:shutdown_watchdog_dev_400000_cw310_rom_with_fake_keys test and the hang_test.c output described in the report. Compare the one-second wait with the reported watchdog count and trace how the CW310 watchdog frequency is determined. Done means the observed count is reconciled with the documented 200 kHz frequency.