The "run_to_completion" mode was somewhat broken.  Locks need to be avoided in
run_to_completion mode, and it shouldn't be used by normal users, just
internally for panic situations.

This patch removes locks in run_to_completion mode and removes the user call
for setting the mode.  The only user was the poweroff code, but it was easily
converted to use the polling interface.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NCorey Minyard <cminyard@mvista.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>