CIFS: Add capability to send SMB2 negotiate message

and add negotiate request type to let set_credits know that
we are only on negotiate stage and no need to make a decision
about disabling echos and oplocks.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index b77e9ec..daf6837 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -16,4 +16,5 @@
 
 cifs-$(CONFIG_CIFS_FSCACHE) += fscache.o cache.o
 
-cifs-$(CONFIG_CIFS_SMB2) += smb2ops.o smb2maperror.o smb2transport.o smb2misc.o
+cifs-$(CONFIG_CIFS_SMB2) += smb2ops.o smb2maperror.o smb2transport.o \
+			    smb2misc.o smb2pdu.o