cxl: Fix leaking interrupts if attach process fails

In this particular error path we have already allocated the AFU
interrupts, but have not yet set the status to STARTED. The detach
context code will only attempt to release the interrupts if the context
is in state STARTED, so in this case the interrupts would remain
allocated.

This patch releases the AFU interrupts immediately if the attach call
fails to prevent them leaking.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>