avocado/boot_linux_console.py: check TCG accel in test_ppc_g3beige()

avocado/boot_linux_console.py: check TCG accel in test_ppc_g3beige()

This test breaks when run in an IBM POWER host with a QEMU compiled
with --disable-tcg and the ppc-softmmu target.

One thing to note is that the error message explictly mentions kvm_pr
support:

Command: ./qemu-system-ppc -display none -vga none (...)
-machine g3beige (...)
        Output: ioctl(KVM_CREATE_VM) failed: 22 Invalid argument
PPC KVM module is not loaded. Try modprobe kvm_pr.
qemu-system-ppc: failed to initialize kvm: Invalid argument

The host was running kvm_hv, not kvm_pr, and the machine failed to load.

Unfortunately we don't have a way to detect whether the KVM module loaded
is kvm_hv or kvm_pr - we do a check for /dev/kvm to detect KVM support but
both modules create this file so that's not helpful.

Let's skip this test for now until we have a way of detecting kvm_pr support in the host.

Reported-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220310183011.110391-2-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>