mtd: tests: incorporate error message for mtdtest_read()

All callers of mtdtest_read() print the same error message on failure.
This incorporates the error message to mtdtest_read() and removes them
from the callers.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/tests/mtd_test.c

@@ -92,6 +92,8 @@ int mtdtest_read(struct mtd_info *mtd, loff_t addr, size_t size, void *buf)
 		err = 0;
 	if (!err && read != size)
 		err = -EIO;
+	if (err)
+		pr_err("error: read failed at %#llx\n", addr);
 
 	return err;
 }