cifs: fix cifsConvertToUCS() for the mapchars case

As Metze pointed out, commit 84cdf74e broke mapchars option:

Commit "cifs: fix unaligned accesses in cifsConvertToUCS"
(84cdf74e8096a10dd6acbb870dd404b92f07a756) does multiple steps
in just one commit (moving the function and changing it without
testing).

put_unaligned_le16(temp, &target[j]); is never called for any
codepoint the goes via the 'default' switch statement. As a result
we put just zero (or maybe uninitialized) bytes into the target
buffer.

His proposed patch looks correct, but doesn't apply to the current head
of the tree. This patch should also fix it.

Cc: <[e-mail]> # .38.x: 581ade4: cifs: clean up various nits in unicode routines (try #2)
Reported-by: Stefan Metzmacher <[e-mail]>
Signed-off-by: Jeff Layton <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/cifs_unicode.c

···
 
 	for (i = 0, j = 0; i < srclen; j++) {
 		src_char = source[i];
+		charlen = 1;
 		switch (src_char) {
 		case 0:
 			put_unaligned(0, &target[j]);
···
 				dst_char = cpu_to_le16(0x003f);
 				charlen = 1;
 			}
-			/*
-			 * character may take more than one byte in the source
-			 * string, but will take exactly two bytes in the
-			 * target string
-			 */
-			i += charlen;
-			continue;
 		}
+		/*
+		 * character may take more than one byte in the source string,
+		 * but will take exactly two bytes in the target string
+		 */
+		i += charlen;
 		put_unaligned(dst_char, &target[j]);
-		i++; /* move to next char in source string */
 	}
 
 ctoUCS_out: