genirq/msi: Drop artificial PCI dependency

The generic MSI layer doesn't have any PCI ties anymore, and the
build hack should have been removed some time ago.

Fixes: d9109698 ("genirq: Introduce msi_domain_alloc/free_irqs()")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1479806476-20801-1-git-send-email-marc.zyngier@arm.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/irq/msi.c

@@ -14,9 +14,7 @@
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/msi.h>
-
-/* Temparory solution for building, will be removed later */
-#include <linux/pci.h>
+#include <linux/slab.h>
 
 /**
  * alloc_msi_entry - Allocate an initialize msi_entry