Char: isicom, cleanup locking

Don't spin processor when not needed (use sleep instead of delay).  Don't
release the lock when needed in next iteration -- this actually fixes a bug --
missing braces

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>