tests/functional/test_arm_orangepi: rename test class to 'OrangePiMachine'

tests/functional/test_arm_orangepi: rename test class to 'OrangePiMachine'

The test class in this file contains all functional test cases
for testing the Orange Pi PC board. It should be given a name
matching the Qemu machine it covers.

This commit sets the test class name to 'OrangePiMachine'.

Signed-off-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Fixes: 380f7268b7b ("tests/functional: Convert the OrangePi tests to the  functional framework")
Message-ID: <20250316210232.46298-1-nieklinnenbank@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>