block: use linux/uaccess.h in elevator.c instead of asm variant

#include <linux/delay.h>

#include <linux/delay.h>

#include <linux/blktrace_api.h>

#include <linux/blktrace_api.h>

#include <linux/hash.h>

#include <linux/hash.h>

#include <linux/uaccess.h>

#include <asm/uaccess.h>

static DEFINE_SPINLOCK(elv_list_lock);

static DEFINE_SPINLOCK(elv_list_lock);

static LIST_HEAD(elv_list);

static LIST_HEAD(elv_list);