amd64_edac: Do not report error overflow as a separate error

When the Overflow MCi_STATUS bit is set, EDAC reports the lost error
with a "no information available" message which often puzzles users
parsing the dmesg. This doesn't make much sense since this error has
been lost anyway so no need for reporting it separately. Thus, report
the overflow bit setting in the MCE dump instead. While at it, remove
reporting of MiscV and ErrorEnable (en) which are superfluous.

Now it looks like this:

[ 1501.650024] MC4_STATUS: Corrected error, other errors lost: yes, CPU context corrupt: no, CECC Error
[ 1501.666887] Northbridge Error, node 2

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>