mtd: nand: remove kerneldoc for removed function parameter

The 'getchip' parameter is gone as of commit 9f3e0429 ("mtd: nand:
don't select chip in nand_chip's block_bad op"), so kill the doc with
it.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/nand_base.c

@@ -313,7 +313,6 @@ static void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
  * nand_block_bad - [DEFAULT] Read bad block marker from the chip
  * @mtd: MTD device structure
  * @ofs: offset from device start
- * @getchip: 0, if the chip is already selected
  *
  * Check, if the block is bad.
  */