In preparation to enabling -Wimplicit-fallthrough, mark switch cases where
we are expecting to fall through.

Notice that, in this particular case, I replaced "Drop thru" and "Fall
Thru" with "fall through" annotations, which is what GCC is expecting to
find.

Also, in some cases a dash is added as a token in order to separate the
"fall through" annotation from the rest of the comment on the same line,
which is what GCC is expecting to find.

Addresses-Coverity-ID: 114979 ("Missing break in switch")
Addresses-Coverity-ID: 114980 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>