console: Simplify the enable rules

Consoles on CBMEM and USB have somewhat complex rules and dependencies
when they can be active. Use simple variables to test which stage
of boot is being built for each console.

Change-Id: I2489e7731d07ca7d5dd2ea8b6501c73f05d6edd8
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5341
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
8 files changed