io_uring/region: return negative -E2BIG in io_create_region()

This code accidentally returns positivie E2BIG instead of negative
-E2BIG.  The callers treat negatives and positives the same so this
doesn't affect the kernel.  The error code is returned to userspace via
the system call.

Fixes: dfbbfbf ("io_uring: introduce concept of memory regions")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/d8ea3bef-74d8-4f77-8223-6d36464dd4dc@stanley.mountain
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Dan Carpenter

io_uring/memmap.c

@@ -229,7 +229,7 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
 	if (!reg->size || reg->mmap_offset || reg->id)
 		return -EINVAL;
 	if ((reg->size >> PAGE_SHIFT) > INT_MAX)
-		return E2BIG;
+		return -E2BIG;
 	if ((reg->user_addr | reg->size) & ~PAGE_MASK)
 		return -EINVAL;
 	if (check_add_overflow(reg->user_addr, reg->size, &end))