checkpatch: always check block comment styles

Some of the block comment tests that are used only for networking are
appropriate for all patches.

For example, these styles are not encouraged:

	/*
	 block comment without introductory *
	*/
and
	/*
	 * block comment with line terminating */

Remove the networking specific test and add comments.

There are some infrequent false positives where code is lazily
commented out using /* and */ rather than using #if 0/#endif blocks
like:
	/* case foo:
	case bar: */
	case baz:

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>