console: Simplify bootblock console Kconfig selection logic

Instead of depending BOOTBLOCK_CONSOLE on a set of architectures,
allow the arch or platform to specify whether it can provide a C
environment. This simplifies the selection logic.

Change-Id: Ia3e41796d9aea197cee0a073acce63761823c3aa
Signed-off-by: Alexandru Gagniuc <alexandrux.gagniuc@intel.com>
Reviewed-on: https://review.coreboot.org/12871
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
6 files changed