hw/block/pflash_cfi02: Document 'Page Mode' operations are not supported

The 'page mode' feature entry was implicitly set as zero
(not supported). Document it exists, so we won't discard
it if we squeeze the CFI table.

Signed-off-by: Stephen Checkoway <stephen.checkoway@oberlin.edu>
Message-Id: <20190426162624.55977-6-stephen.checkoway@oberlin.edu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[PMD: Extracted from bigger patch]
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/block/pflash_cfi02.c

@@ -637,7 +637,9 @@ static void pflash_cfi02_realize(DeviceState *dev, Error **errp)
     pfl->cfi_table[0x0a + pri_ofs] = 0x00;
     /* Burst mode not supported. */
     pfl->cfi_table[0x0b + pri_ofs] = 0x00;
-    assert(0x0b + pri_ofs < ARRAY_SIZE(pfl->cfi_table));
+    /* Page mode not supported. */
+    pfl->cfi_table[0x0c + pri_ofs] = 0x00;
+    assert(0x0c + pri_ofs < ARRAY_SIZE(pfl->cfi_table));
 }
 
 static Property pflash_cfi02_properties[] = {