kunit: qemu_configs: Add PowerPC 32-bit BE and 64-bit LE

Add basic configs to run kunit tests on some more PowerPC variants.

Link: https://lore.kernel.org/r/20250415-kunit-ppc-v1-2-f5a170264147@linutronix.de


Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>