EDAC: Fix wrong executable file modes for C source files

Three EDAC source files were mistakenly marked as executable when adding the
EDAC scrub controls.

These are plain C source files and should not carry the executable bit.
Correcting their modes follows the principle of least privilege and avoids
unnecessary execute permissions in the repository.

[ bp: Massage commit message. ]

Signed-off-by: Kuan-Wei Chiu <[e-mail]>
Signed-off-by: Borislav Petkov (AMD) <[e-mail]>
Link: https://lore.kernel.org/[e-mail]