x86/mm: Refine mmap syscall implementation

It is unnecessary to use the local variable 'error' in the mmap syscall
implementation function - just return -EINVAL directly and get rid of
the local variable altogether.

 [ bp: Massage commit message. ]
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20201217052648.24656-1-adrianhuang0701@gmail.com

arch/x86/kernel/sys_x86_64.c

@@ -90,14 +90,10 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 		unsigned long, prot, unsigned long, flags,
 		unsigned long, fd, unsigned long, off)
 {
-	long error;
-	error = -EINVAL;
 	if (off & ~PAGE_MASK)
-		goto out;
+		return -EINVAL;
 
-	error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
-out:
-	return error;
+	return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
 }
 
 static void find_start_end(unsigned long addr, unsigned long flags,