am335x-evm: Fix spiboot configuration

The advanced address translation provided by CONFIG_SPL_OF_TRANSLATE is
needed to determine the base address of the uart0 peripheral on am335x
platforms when CONFIG_SPL_OF_CONTROL is enabled.

If CONFIG_SPL_OF_CONTROL is enabled in the base (non-spiboot)
am335x_evm_defconfig, then CONFIG_SPL_OF_TRANSLATE will also need to be
enabled there. Unfortunately this cannot be done pre-emptively due to
the kconfig dependencies.

The TI clk-ctrl & TI sysc drivers are also required to bring up the SPI
bus on am335x platforms.

Signed-off-by: Paul Barker <paul.barker@sancloud.com>