The cleanup code of spi_nor_erase() function calls write_disable(), but
does not return it's return value even in case of failure. Fix this.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>