kernel.h: fix might_sleep kernel-doc

Put the kernel-doc for might_sleep() _immediately_ before the macro
(no intervening lines).  Otherwise kernel-doc complains like so:

Warning(linux-2.6.27-rc3-git2//include/linux/kernel.h:129): No description found for parameter 'file'
Warning(linux-2.6.27-rc3-git2//include/linux/kernel.h:129): No description found for parameter 'line'

because kernel-doc is looking at the wrong function prototype (i.e.,
__might_sleep).  [Yes, I have a todo note to myself to check/warn for that
inconsistency in scripts/kernel-doc.]

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>