dz: handle special conditions on reception correctly

Handle the read and ignore status masks correctly.  Handle the BREAK condition
as expected: a framing error with a null character is a BREAK, any other
framing error is a framing error indeed.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/serial/dz.h

@@ -33,6 +33,8 @@
 #define DZ_FERR        0x2000                 /* Frame error indicator */
 #define DZ_PERR        0x1000                 /* Parity error indicator */
 
+#define DZ_BREAK       0x0800                 /* BREAK event software flag */
+
 #define LINE(x) ((x & DZ_LINE_MASK) >> 8)     /* Get the line number
                                                  from the input buffer */
 #define UCHAR(x) ((unsigned char)(x & DZ_RBUF_MASK))