tests: Boot and halt a Linux guest on the Raspberry Pi 2 machine

tests: Boot and halt a Linux guest on the Raspberry Pi 2 machine

Add a test booting and quickly shutdown a raspi2 machine,
to test the power management model:

   (1/1) tests/acceptance/boot_linux_console.py:BootLinuxConsole.test_arm_raspi2_initrd:
  console: [    0.000000] Booting Linux on physical CPU 0xf00
  console: [    0.000000] Linux version 4.14.98-v7+ (dom@dom-XPS-13-9370) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1200 SMP Tue Feb 12 20:27:48 GMT 2019
  console: [    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c5387d
  console: [    0.000000] CPU: div instructions available: patching division code
  console: [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
  console: [    0.000000] OF: fdt: Machine model: Raspberry Pi 2 Model B
  ...
  console: Boot successful.
  console: cat /proc/cpuinfo
  console: / # cat /proc/cpuinfo
  ...
  console: processor      : 3
  console: model name     : ARMv7 Processor rev 5 (v7l)
  console: BogoMIPS       : 125.00
  console: Features       : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
  console: CPU implementer        : 0x41
  console: CPU architecture: 7
  console: CPU variant    : 0x0
  console: CPU part       : 0xc07
  console: CPU revision   : 5
  console: Hardware       : BCM2835
  console: Revision       : 0000
  console: Serial         : 0000000000000000
  console: cat /proc/iomem
  console: / # cat /proc/iomem
  console: 00000000-3bffffff : System RAM
  console: 00008000-00afffff : Kernel code
  console: 00c00000-00d468ef : Kernel data
  console: 3f006000-3f006fff : dwc_otg
  console: 3f007000-3f007eff : /soc/dma@7e007000
  console: 3f00b880-3f00b8bf : /soc/mailbox@7e00b880
  console: 3f100000-3f100027 : /soc/watchdog@7e100000
  console: 3f101000-3f102fff : /soc/cprman@7e101000
  console: 3f200000-3f2000b3 : /soc/gpio@7e200000
  PASS (24.59 s)
  RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
  JOB TIME   : 25.02 s

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Message-id: 20210531113837.1689775-1-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>