EDAC/altera: Test the correct error reg offset

EDAC/altera: Test the correct error reg offset

Test correct structure member, ecc_cecnt_offset, before using it.

  [ bp: Massage commit message. ]

Fixes: 73bcc942f427 ("EDAC, altera: Add Arria10 EDAC support")
Signed-off-by: Niravkumar L Rabara <niravkumar.l.rabara@altera.com>
Signed-off-by: Matthew Gerlach <matthew.gerlach@altera.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Cc: stable@kernel.org
Link: https://lore.kernel.org/20250425142640.33125-2-matthew.gerlach@altera.com