ARM: zynq: Don't select CONFIG_ICST

CONFIG_ICST is for ARM Ltd reference platforms and isn't used by Zynq
platform, so remove selecting it. It appears to be a copy-n-paste error.

Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Rob Herring <robh@kernel.org>
[arnd: remove the versatile clk driver change I added previously]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>