timers/migration: Convert "while" loops to use "for"

timers/migration: Convert "while" loops to use "for"

[ Upstream commit 6c181b5667eea3e6564d334443536a5974190e15 ]

Both the "do while" and "while" loops in tmigr_setup_groups() eventually
mimic the behaviour of "for" loops.

Simplify accordingly.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251024132536.39841-2-frederic@kernel.org
Stable-dep-of: 5eb579dfd46b ("timers/migration: Fix imbalanced NUMA trees")
Signed-off-by: Sasha Levin <sashal@kernel.org>