ipc, msg: forbid negative values for "msg{max,mnb,mni}"

Negative message lengths make no sense -- so don't do negative queue
lenghts or identifier counts. Prevent them from getting negative.

Also change the underlying data types to be unsigned to avoid hairy
surprises with sign extensions in cases where those variables get
evaluated in unsigned expressions with bigger data types, e.g size_t.

In case a user still wants to have "unlimited" sizes she could just use
INT_MAX instead.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

Pull MIPS fixes from Ralf Baechle:
 "Three fixes across arch/mips with the most complex one being the GIC
  interrupt fix - at nine lines still not monster.  I'm confident this
  are the final MIPS patches even if there should go for an rc8"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: ralink: fix return value check in rt_timer_probe()
  MIPS: malta: Fix GIC interrupt offsets
  MIPS: Perf: Fix 74K cache map
Linux 3.12