RAS/CEC: Remove a repeated 'an' in a comment

The double `an' in the comment in line 41 is repeated. Remove one of
them.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211211091914.268823-1-wangborong@cdjrlc.com