x86: Fix a typo

legact -> legacy

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/sys_x86_64.c

@@ -157,7 +157,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (flags & MAP_FIXED)
 		return addr;
 
-	/* for MAP_32BIT mappings we force the legact mmap base */
+	/* for MAP_32BIT mappings we force the legacy mmap base */
 	if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT))
 		goto bottomup;