mtd: spi: Add 'struct spi_flash {' to the code

At present spi_flash is defined to be spi_nor which is confusing since it
is not possible to find the 'spi_flash' by normal text search. Add a
comment to help with this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
1 file changed