The flash on the Integrator was already defined by the device
tree, but VPP control and flash protection was in the
boardfiles. Simply add the compatible string
"arm,versatile-flash" and the special add-on code for flash
programming voltage and protection kicks in in the MTD
layer.

Remove the board file code and augment the device tree in
one go for seamless transition.

Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>