net: hns: fix unsigned comparison to less than zero

[ Upstream commit ea401685 ]

Currently mskid is unsigned and hence comparisons with negative
error return values are always false. Fix this by making mskid an
int.

Fixes: f058e468

 ("net: hns: fix ICMP6 neighbor solicitation messages discard problem")
Addresses-Coverity: ("Operands don't affect result")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>