misc: pci_endpoint_test: Use full pci-endpoint-test name in request_irq()

Use full pci-endpoint-test name in request_irq(), so that it's easy to
profile the device that actually raised the interrupt.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>