console: Change BOOTBLOCK_CONSOLE default to y

Invert the default instead of selecting it everywhere. Restores the
ability to use its Kconfig prompt.

Beside Qemu targets, the only platforms that didn't select it seem
to be samsung/exynos5420, intel/cannonlake, and intel/icelake. The
latter two were about to be patched anyway.

Change-Id: I7c5b671b7dddb5c6535c97c2cbb5f5053909dc64
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/30891
Reviewed-by: Lijian Zhao <lijian.zhao@intel.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/console/Kconfig

@@ -3,7 +3,7 @@ menu "Console"
 config BOOTBLOCK_CONSOLE
 	bool "Enable early (bootblock) console output."
 	depends on C_ENVIRONMENT_BOOTBLOCK
-	default n
+	default y
 	help
 	  Use console during the bootblock if supported