locking/lockdep: Enforce PROVE_RAW_LOCK_NESTING only if ARCH_SUPPORTS_RT

Relax the rule to set PROVE_RAW_LOCK_NESTING by default only for arches
that supports PREEMPT_RT.  For arches that do not support PREEMPT_RT,
they will not be forced to address unimportant raw lock nesting issues
when they want to enable PROVE_LOCKING.  They do have the option
to enable it to look for these raw locking nesting problems if they
choose to.

Suggested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20241128020009.83347-1-longman@redhat.com