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

Notice that I replaced "!! fall through !!" and "!!! fall through !!!"
comments with "fall through" annotations, which is what GCC is expecting to
find.

Addresses-Coverity-ID: 744899 ("Missing break in switch")
Addresses-Coverity-ID: 744900 ("Missing break in switch")
Addresses-Coverity-ID: 744901 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Sudarsana Kalluru <Sudarsana.Kalluru@qlogic.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>