pcie: msi: add generic MSI vector entry
pcie: msi: add generic MSI vector entry

Define a generic MSI vector entry to be used with the Generic PCIe
Controller API.

Signed-off-by: Neil Armstrong <619b324efbf5f7848de055bdc8bef4c0dd7c8ef5@baylibre.com>

galak/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr