Revert "sched/tune: Initialize raw_spin_lock in boosted_groups"

This reverts commit 10003c8a.

The per-cpu boost_groups locks are already initilized in the
schedtune_init_cgroups() call where schedtune_initialized is set to
true.

Bug: 62272775
Change-Id: Iedf392ce667e28e709c229d5d769eef5b05f9bc9
Signed-off-by: David Lin <dtwlin@google.com>