local_lock: Move this_cpu_ptr() notation from internal to main header

local_lock.h is the main header for the local_lock_t type and provides
wrappers around internal functions prefixed with __ in
local_lock_internal.h.

Move the this_cpu_ptr() dereference of the variable from the internal to
the main header. Since it is all macro implemented, this_cpu_ptr() will
still happen within the preempt/ IRQ disabled section.

This frees the internal implementation (__) to be used on local_lock_t
types which are local variables and must not be accessed via
this_cpu_ptr().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250630075138.3448715-2-bigeasy@linutronix.de