BootLinuxConsoleTest: Run kerneltests BusyBox on Malta

BootLinuxConsoleTest: Run kerneltests BusyBox on Malta

This tests boots a Linux kernel on a Malta machine up to a
busybox shell on the serial console. Few commands are executed
before halting the machine (via reboot).

We use the initrd cpio image from the kerneltests project:
https://kerneltests.org/

If MIPS is a target being built, "make check-acceptance" will
automatically include this test by the use of the "arch:mips" tags.

Alternatively, this test can be run using:

  $ avocado --show=console run -t arch:mips tests/acceptance/boot_linux_console.py
  [...]
  console: Boot successful.
  [...]
  console: / # uname -a
  console: Linux buildroot 4.5.0-2-4kc-malta #1 Debian 4.5.5-1 (2016-05-29) mips GNU/Linux
  console: / # reboot
  console: / # reboot: Restarting system

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20190520231910.12184-4-f4bug@amsat.org>
Acked-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>