EDAC/mce_amd: Fix typo "FIfo" -> "Fifo"

There is an uppercase letter I in one of the MCE error descriptions
instead of a lowercase one. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Link: https://lkml.kernel.org/r/20210603103349.79117-1-colin.king@canonical.com