arm: zynq: Move to select'ing ARCH_EARLY_INIT_R if we have FPGA

arm: zynq: Move to select'ing ARCH_EARLY_INIT_R if we have FPGA

The function arch_early_init_r only does anything on these platforms if
we have FPGA (or SPL and SPL_FPGA) enabled, so move the logic to select
based on that.

Cc: Michal Simek <michal.simek@amd.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Simon Glass <sjg@chromium.org>