Dustin,
I thought that you are using the no-OS driver...sorry. If you want to change the LO frequency from Linux, you can write the desired frequency value to /sys/bus/iio/devices/adf4351-rx-lpc/out_altvoltage0_frequency for RX or to /sys/bus/iio/devices/adf4351-tx-lpc/out_altvoltage0_frequency for TX. For more information take a look over the ADF4350 driver description: http://wiki.analog.com/resources/tools-software/linux-drivers/iio-pll/adf4350#hardware_configuration
I suggest you, before compiling your own kernel and creating a new SD card image, to also play with our image: https://wiki.analog.com/resources/tools-software/linux-software/zynq_images
Regards,
Dragos