atapi: cleanup/fix mode sense results

The first two bytes (after the 8-byte ATAPI header) are the mode page
number and the number of bytes after the length field itself.  Make
this clear in the code.

The AUDIO_CTL page was filled with wrong values.  It is not anymore in
MMC, but at least keep the values sane.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/ide/atapi.c

@@ -711,8 +711,8 @@ static void cmd_mode_sense(IDEState *s, uint8_t *buf)
             buf[6] = 0;
             buf[7] = 0;
 
-            buf[8] = 0x01;
-            buf[9] = 0x06;
+            buf[8] = MODE_PAGE_R_W_ERROR;
+            buf[9] = 16 - 10;
             buf[10] = 0x00;
             buf[11] = 0x05;
             buf[12] = 0x00;
@@ -730,6 +730,8 @@ static void cmd_mode_sense(IDEState *s, uint8_t *buf)
             buf[6] = 0;
             buf[7] = 0;
 
+            buf[8] = MODE_PAGE_AUDIO_CTL;
+            buf[9] = 24 - 10;
             /* Fill with CDROM audio volume */
             buf[17] = 0;
             buf[19] = 0;
@@ -747,8 +749,8 @@ static void cmd_mode_sense(IDEState *s, uint8_t *buf)
             buf[6] = 0;
             buf[7] = 0;
 
-            buf[8] = 0x2a;
-            buf[9] = 0x12;
+            buf[8] = MODE_PAGE_CAPABILITIES;
+            buf[9] = 28 - 10;
             buf[10] = 0x00;
             buf[11] = 0x00;