PCI/MSI: Enable PCI_MSI_IRQ_DOMAIN support for ARC

Add ARC as an arch that supports PCI_MSI_IRQ_DOMAIN and add generation of
msi.h in the ARC arch.
Signed-off-by: Joao Pinto <jpinto@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/Kbuild

@@ -25,6 +25,7 @@ generic-y += mcs_spinlock.h
 generic-y += mm-arch-hooks.h
 generic-y += mman.h
 generic-y += msgbuf.h
+generic-y += msi.h
 generic-y += param.h
 generic-y += parport.h
 generic-y += pci.h

drivers/pci/Kconfig

@@ -25,7 +25,7 @@ config PCI_MSI
 	   If you don't know what to do here, say Y.
 
 config PCI_MSI_IRQ_DOMAIN
-	def_bool ARM || ARM64 || X86
+	def_bool ARC || ARM || ARM64 || X86
 	depends on PCI_MSI
 	select GENERIC_MSI_IRQ_DOMAIN