Revert "sched/wait: Suppress Sparse 'variable shadowing' warning"

This reverts commit 980f88e4

.

This warning is actually useful, don't suppress it.

We actually rely on the shadowing for ___wait_cond_timeout().

We further used the __ret variable in __wait_event_timeout()'s cmd
argument: __ret = schedule_timeout(__ret). That now explicitly uses the
wrong __ret.

Reported-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Requested-by: Andrew Morton <akpm@linux-foundation.org>
Requested-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-Q5blhuqqzwgVwvjf1gszrdol@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>