cfi_flash: use specific width types for cword

cfi_flash: use specific width types for cword

This patch changes the cword union to use specific length types that are
architecture indepented.

This patch also renames the members of the cword union to represent
their usage, i.e.:

    c  -> w8
    s  -> w16
    l  -> w32
    ll -> w64

Where "w" stands for "width" in bits.

I discovered this problem when enabling CFI flash on vexpress64.
cword.l was an unsigned long int, but it was intended to be 32 bits wide.
Unfortunately, it's 64-bits wide on a 64-bit system, meaning that a
64-bit system fails when attempting to use 32-bit wide CFI flash parts.

Similar problems also existed with the other cword sizes.

Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stefan Roese <sr@denx.de>