dts: bindings: pcie: update interrupt-map type to compound

The interrupt-map property specifies both 32-bits values and a phandle;
update the type accordingly.

Update the definition of pcie-host-ecam-generic on qemu arm64 to match
the new type.

Signed-off-by: Rodrigo Cataldo <rodrigo.cataldo@huawei.com>
Co-authored-by: Henri Xavier <datacomos@huawei.com>