modprobe-small: fix and simplify rmmod

modprobe-small: fix and simplify rmmod

"rmmod OUT_OF_TREE_MODULE" was not working, because module is not in depmod file.

In general, rmmod doesn't need scanning, it simply unloads every argv[i].

function                                             old     new   delta
rmmod                                                  -      63     +63
modprobe_main                                        449     465     +16
process_module                                       705     667     -38
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 79/-38)             Total: 41 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>