This moves the boardfile definition of the flash memory in the
Versatile board into the device tree. The flash was already
defined with the property "arm,versatile-flash" which was
not handled by the kernel: instead define it as compatible
also with "cfi-flash" so it detects properly, and delete the
corresponding boardfile code so we get a smooth transition.

The old compatible string "arm,versatile-flash" is reused to
indicate to the MTD physmap subsystem that this flash requires
special VPP handling. (See separate patch.)

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>