Pass a smb_ntlmh* to functions instead of a smb_ntlmh itself

Since smb_ntlmh is typedeffed to uint8_t[SMB_NTLM_HASH_SIZE],
this will actually send the exact same pointer, but clang warns
about the difference in type signature.

Technically, all functions taking a 'smb_ntlmh*' could just as well
be taking a 'smb_ntlmh' instead.