ARM: dts: nomadik: Cut FSMC timings

After the work done by Thomas Petazzoni, the NAND chip timings
can be read out from the chip instead of open coded in the
device tree, so let's just remove the timing information.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>