hw/block/pflash_cfi02: Use chip erase time specified in the CFI table

When erasing the chip, use the typical time specified in the CFI table
rather than arbitrarily selecting 5 seconds.

Since the currently unconfigurable value set in the table is 12, this
means a chip erase takes 4096 ms so this isn't a big change in behavior.

Signed-off-by: Stephen Checkoway <stephen.checkoway@oberlin.edu>
Message-Id: <20190426162624.55977-11-stephen.checkoway@oberlin.edu>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/block/pflash_cfi02.c

@@ -617,9 +617,9 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
                 pflash_update(pfl, 0, pfl->chip_len);
             }
             set_dq7(pfl, 0x00);
-            /* Let's wait 5 seconds before chip erase is done */
+            /* Wait the time specified at CFI address 0x22. */
             timer_mod(&pfl->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
-                      (NANOSECONDS_PER_SECOND * 5));
+                      (1ULL << pfl->cfi_table[0x22]) * SCALE_MS);
             break;
         case 0x30:
             /* Sector erase */