platform/chrome: chromeos_pstore: Add ecc_size module parameter

platform/chrome: chromeos_pstore: Add ecc_size module parameter

On ChromiumOS devices, the `ecc_size` is set to 0 (check dmesg | grep ecc 
to see `ecc: 0`): this disables ECC for ramoops region, even when 
`ramoops.ecc=1` is given to kernel command line parameter.

Introduce `ecc_size` module parameter to provide a method to turn on ECC
for ramoops and set different values of ecc_size per devices.

A large `ecc_size` value can cause a kernel panic due to a constraint in
Reed-Solomon code library. The validation for this constraint should
belong to the common pstore RAM layer, not in each individual driver. So
this check is handled by a separate patch [1].

[1] https://lore.kernel.org/lkml/20250620054757.1006729-1-naoyatezuka@chromium.org

Signed-off-by: Naoya Tezuka <naoyatezuka@chromium.org>
Link: https://lore.kernel.org/r/20250620062822.1018798-1-naoyatezuka@chromium.org
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>