jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE

JUMP_LABEL_NOP_SIZE is now unused, remove it.

Fixes: 001951be ("jump_label, x86: Add variable length patching support")
Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00zxsvocDV5vLU@hirez.programming.kicks-ass.net