hw/block/pflash_cfi01: Report correct size info for parallel configs

hw/block/pflash_cfi01: Report correct size info for parallel configs

If the flash device is configured with a device-width which is
not equal to the bank-width, indicating that it is actually several
narrow flash devices in parallel, the CFI table should report the
number of blocks and the size of a single device, not of the whole
combined setup. This stops Linux from complaining:
"NOR chip too large to fit in mapping. Attempting to cope..."

As usual, we retain the old broken but backwards compatible behaviour
when the device-width is not specified.

Reviewed-by: Peter Crosthwaite <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>
Message-id: 1402409025[email protected]