It seems that after moving to mach-zynq, you couldn't
configure the kernel with xilinx_defconfig, then go back
to mach-xilinx just by selecting the system type as it
would create a .config that caused compile errors.
This is a minor change that turns on V7 for the CPU for
ARCH_XILINX so you can go back as I don't want to break
all the old stuff just because we moved to the new.
config ARCH_XILINX
bool "Xilinx ARM Cortex A9 based FPGA"
+ select CPU_V7
select GENERIC_TIME
select GENERIC_CLOCKEVENTS
select CLKDEV_LOOKUP