uboot_env: nand: fix return of devread

When the function devread read the environement
from a nand, the value returned is always 0. But,
the check on the value returned is done on the
environment size, so we return the size of data
read.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Acked-by: Stefano Babic <sbabic@denx.de>

src/uboot_env.c

@@ -274,8 +274,8 @@ static int devread(struct uboot_ctx *ctx, unsigned int copy, void *data)
 			start += dev->sectorsize;
 			data += blocksize;
 			count -= blocksize;
+			ret += blocksize;
 		}
-		ret = count;
 		break;
 	}