cifs: Fix sparse warning when calling cifs_strtoUCS

Fix sparse endian check warning while calling cifs_strtoUCS

CHECK   fs/cifs/smbencrypt.c
fs/cifs/smbencrypt.c:216:37: warning: incorrect type in argument 1
(different base types)
fs/cifs/smbencrypt.c:216:37:    expected restricted __le16 [usertype] *<noident>
fs/cifs/smbencrypt.c:216:37:    got unsigned short *<noident>

Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>