serial: Setup serial base and freq for zynq/zynqmp

Setup default values for debug console, base address and frequency.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/ce93efd3ed67aa6390810ce0b79e0d00e7c36b4b.1652871485.git.michal.simek@amd.com