smb: client: improve error message when creating SMB session

smb: client: improve error message when creating SMB session

When failing to create a new SMB session with 'sec=krb5' for example,
the following error message isn't very useful

	CIFS: VFS: \\srv Send error in SessSetup = -126

Improve it by printing the following instead on dmesg

	CIFS: VFS: \\srv failed to create a new SMB session with Kerberos: -126

Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: Pierguido Lambri <plambri@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>