PCI/MSI: Use bullet lists in kernel-doc comments of api.c

Use bullet-list RST syntax for kernel-doc parameters' flags and interrupt
mode descriptions. Otherwise Sphinx produces "Unexpected identation" errors
and warnings.

Fixes: 5c0997dc ("PCI/MSI: Move pci_alloc_irq_vectors() to api.c")
Fixes: 017239c8 ("PCI/MSI: Move pci_irq_vector() to api.c")
Fixes: be37b842 ("PCI/MSI: Move pci_irq_get_affinity() to api.c")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ahmed S. Darwish <darwi@linutronix.de>
Link: https://lore.kernel.org/r/20221203100511.222136-1-bagasdotme@gmail.com