mtd: nand: rename the id field of 'struct nand_flash_dev'

The 'id' is a bit confusing name because NAND IDs are multi-byte. Re-name
it to 'dev_id' to make it clear that this is the "device ID" part (the second
byte).

While on it, clean-up the commentary for 'struct nand_flash_dev'.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index 37ee75c..dec80ca 100644
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -989,7 +989,7 @@
 	}
 
 	pxa3xx_flash_ids[0].name = f->name;
-	pxa3xx_flash_ids[0].id = (f->chip_id >> 8) & 0xffff;
+	pxa3xx_flash_ids[0].dev_id = (f->chip_id >> 8) & 0xffff;
 	pxa3xx_flash_ids[0].pagesize = f->page_size;
 	chipsize = (uint64_t)f->num_blocks * f->page_per_block * f->page_size;
 	pxa3xx_flash_ids[0].chipsize = chipsize >> 20;