x86/alternatives: Rename 'text_poke_loc_init()' to 'text_poke_int3_loc_init()'

This name is actively confusing as well, because the simple text_poke*()
APIs use MM-switching based code patching, while text_poke_loc_init()
is part of the INT3 based text_poke_int3_*() machinery that is an
additional layer of functionality on top of regular text_poke*() functionality.

Rename it to text_poke_int3_loc_init() to make it clear which layer
it belongs to.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250411054105.2341982-18-mingo@kernel.org