nfc: llcp: use centralized exiting of bind on errors

Coding style encourages centralized exiting of functions, so rewrite
llcp_sock_bind() error paths to use such pattern.  This reduces the
duplicated cleanup code, make success path visually shorter and also
cleans up the errors in proper order (in reversed way from
initialization).

No functional impact expected.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>