drivers/mtd: add MTDIOC_ISBAD ioctl

add an ioctl item MTDIOC_ISBAD
used for flashtool command to check bad blocks

Signed-off-by: zhengyu9 <zhengyu9@xiaomi.com>

include/nuttx/mtd/mtd.h

@@ -85,6 +85,9 @@
                                              * OUT: None
                                              *      Resets the device to the power-on
                                              *      default condition */
+#define MTDIOC_ISBAD        _MTDIOC(0x000e) /* IN: Erase block number
+                                             * OUT: 0=A good block
+                                             *      1=A bad block */
 
 /* Macros to hide implementation */
 
@@ -158,6 +161,14 @@ struct mtd_erase_s
   uint32_t nblocks;     /* Number of blocks to be erased */
 };
 
+/* This structure store the bad block information of a block */
+
+struct mtd_bad_block_s
+{
+  off_t block_num;
+  int bad_flag;
+};
+
 /* This structure defines the interface to a simple memory technology device.
  * It will likely need to be extended in the future to support more complex
  * devices.