nfc: constify several pointers to u8, char and sk_buff

[ Upstream commit 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 ]

Several functions receive pointers to u8, char or sk_buff but do not
modify the contents so make them const.  This allows doing the same for
local variables and in total makes the code a little bit safer.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 0d9b41daa590 ("nfc: llcp: fix possible use of uninitialized variable in nfc_llcp_send_connect()")
Signed-off-by: Sasha Levin <sashal@kernel.org>