Fix that several functions handle incorrect value of mapchars

Cifs client has problem with reserved chars filename.

[BUG1] : several functions handle incorrect value of mapchars
-	cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+	cifs_remap(cifs_sb));

[BUG2] : forget to convert reserved chars when creating SymbolicLink.
-	CIFSUnixCreateSymLink() calls cifs_strtoUTF16
+	CIFSUnixCreateSymLink() calls cifsConvertToUTF16() with remap

[BUG3] : forget to convert reserved chars when getting SymbolicLink.
-	CIFSSMBUnixQuerySymLink() calls cifs_strtoUTF16
+	CIFSSMBUnixQuerySymLink() calls cifsConvertToUTF16() with remap

[BUG4] : /proc/mounts don't show "mapposix" when using mapposix mount option
+	    cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
+ 		seq_puts(s, ",mapposix");

Reported-by:  <t.wede@kw-reneg.de>
Reported-by: Nakajima Akira <nakajima.akira@nttcom.co.jp>
Signed-off-by: Nakajima Akira <nakajima.akira@nttcom.co.jp>
Signed-off-by: Carl Schaefer <schaefer@trilug.org>
Signed-off-by: Steve French <smfrench@gmail.com>