The its-trigger test checks that LPI 8195 is not delivered to the CPU while
it is disabled at the ITS level, after which it is re-enabled and tests
that it's now properly asserted. After it is re-enabled it is triggered
again, which can lead to the same interrupt being delivered twice: once
after the configuration invalidation (which re-enables it) and once after
the INT command.

Get rid of the INT command after it is re-enabled to prevent the LPI from
being asserted twice and add a separate check to test that the INT command
still works for the LPI.