misc: at25: Check proper value of chip length in FRAM case

Obviously the byte_len value should be checked from the chip
and not from at25->chip.

Fixes: fd307a4a ("nvmem: prepare basics for FRAM support")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211125212729.86585-4-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>