mdev: fix a bug where it was not stopping on first matching rule
(testsuite entry added). Revamped line parsing while at it.

function                                             old     new   delta
next_field                                             -      36     +36
make_device                                         1104    1022     -82
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 36/-82)            Total: -46 bytes


2 files changed