EDAC/igen6: Fix the flood of invalid error reports

The ECC_ERROR_LOG register of certain SoCs may contain the invalid value
~0, which results in a flood of invalid error reports in polling mode.

Fix the flood of invalid error reports by skipping the invalid ECC error
log value ~0.

Fixes: e14232af ("EDAC/igen6: Add polling support")
Reported-by: Ramses <ramses@well-founded.dev>
Closes: https://lore.kernel.org/all/OISL8Rv--F-9@well-founded.dev/


Tested-by: Ramses <ramses@well-founded.dev>
Reported-by: John <therealgraysky@proton.me>
Closes: https://lore.kernel.org/all/p5YcxOE6M3Ncxpn2-Ia_wCt61EM4LwIiN3LroQvT_-G2jMrFDSOW5k2A9D8UUzD2toGpQBN1eI0sL5dSKnkO8iteZegLoQEj-DwQaMhGx4A=@proton.me/


Tested-by: John <therealgraysky@proton.me>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20250212083354.31919-1-qiuxu.zhuo@intel.com