pflash_cfi01: qemu_log_mask "unimplemented" msg

This printf is informing the user of unimplemented functionality. It should be
re-directed to qemu_log(LOG_UNIMP, ...) accordingly.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

hw/pflash_cfi01.c

diff --git a/hw/pflash_cfi01.c b/hw/pflash_cfi01.c
index 7d040b5..f9f8e5d 100644
--- a/hw/pflash_cfi01.c
+++ b/hw/pflash_cfi01.c
@@ -438,9 +438,9 @@
     return;
 
  error_flash:
-    printf("%s: Unimplemented flash cmd sequence "
-           "(offset " TARGET_FMT_plx ", wcycle 0x%x cmd 0x%x value 0x%x)\n",
-           __func__, offset, pfl->wcycle, pfl->cmd, value);
+    qemu_log_mask(LOG_UNIMP, "%s: Unimplemented flash cmd sequence "
+                  "(offset " TARGET_FMT_plx ", wcycle 0x%x cmd 0x%x value 0x%x)"
+                  "\n", __func__, offset, pfl->wcycle, pfl->cmd, value);
 
  reset_flash:
     memory_region_rom_device_set_readable(&pfl->mem, true);