misc: pci_endpoint_test: Use INTX instead of LEGACY

misc: pci_endpoint_test: Use INTX instead of LEGACY

[ Upstream commit acd288666979a49538d70e0c0d86e1118b445058 ]

In the root complex pci endpoint test function driver, change macros and
functions names using the term "legacy" to use "intx" instead to
match the term used in the PCI specifications.

Link: https://lore.kernel.org/r/20231122060406.14695-6-dlemoal@kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Stable-dep-of: 919d14603dab ("misc: pci_endpoint_test: Fix displaying 'irq_type' after 'request_irq' error")
Signed-off-by: Sasha Levin <sashal@kernel.org>