avocado/ppc_prep_40p.py: check TCG accel in all tests

All tests in the file times out when running in an IBM POWER host and
--disable-tcg with an error like the following:

        Command: ./qemu-system-ppc -display none -vga none (...)
-machine 40p (...)
        Output: qemu-system-ppc: Register sync failed... If you're using
kvm-hv.ko, only "-cpu host" is possible
qemu-system-ppc: kvm_init_vcpu: kvm_arch_init_vcpu failed (0): Invalid argument

Since we don't have a way to detect whether the host is running kvm_hv
or kvm_pr, skip all tests if TCG is not available.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220310183011.110391-9-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

tests/avocado/ppc_prep_40p.py

@@ -28,7 +28,9 @@ def test_factory_firmware_and_netbsd(self):
         :avocado: tags=machine:40p
         :avocado: tags=os:netbsd
         :avocado: tags=slowness:high
+        :avocado: tags=accel:tcg
         """
+        self.require_accelerator("tcg")
         bios_url = ('http://ftpmirror.your.org/pub/misc/'
                     'ftp.software.ibm.com/rs6000/firmware/'
                     '7020-40p/P12H0456.IMG')
@@ -51,7 +53,9 @@ def test_openbios_192m(self):
         """
         :avocado: tags=arch:ppc
         :avocado: tags=machine:40p
+        :avocado: tags=accel:tcg
         """
+        self.require_accelerator("tcg")
         self.vm.set_console()
         self.vm.add_args('-m', '192') # test fw_cfg
 
@@ -65,7 +69,9 @@ def test_openbios_and_netbsd(self):
         :avocado: tags=arch:ppc
         :avocado: tags=machine:40p
         :avocado: tags=os:netbsd
+        :avocado: tags=accel:tcg
         """
+        self.require_accelerator("tcg")
         drive_url = ('https://archive.netbsd.org/pub/NetBSD-archive/'
                      'NetBSD-7.1.2/iso/NetBSD-7.1.2-prep.iso')
         drive_hash = 'ac6fa2707d888b36d6fa64de6e7fe48e'