checkpatch: fix braces {} handling

checkpatch.pl doesn't report warning for if/else statements with missing
'else' braces:

if (something) {
    foo;
} else
    bar;

The patch has been tested using the last 100 commits.

Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
