scripts/coccinelle/misc/semicolon.cocci: Add unneeded semicolon test

This semantic patch looks for semicolons that can be removed without
changing the semantics of the code. The confidence is moderate
because there are some false positives on cases like:

b/drivers/mmc/host/cb710-mmc.c:589
                break;
        case MMC_POWER_UP:
        default:
-               /* ignore */;
        }

There are 37 patches accepted reported by this semantic patch and
more than 300 fixes to be applied.

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>