PCI: Turn pcibios_penalize_isa_irq() into a weak function

pcibios_penalize_isa_irq() is only implemented by x86 now, and legacy ISA
is not used by some architectures.  Make pcibios_penalize_isa_irq() a
__weak function to simplify the code.  This removes the need for new
platforms to add stub implementations of pcibios_penalize_isa_irq().

[bhelgaas: changelog, comments]
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3901283..11f2491 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1468,6 +1468,17 @@
  */
 void __weak pcibios_disable_device (struct pci_dev *dev) {}
 
+/**
+ * pcibios_penalize_isa_irq - penalize an ISA IRQ
+ * @irq: ISA IRQ to penalize
+ * @active: IRQ active or not
+ *
+ * Permits the platform to provide architecture-specific functionality when
+ * penalizing ISA IRQs. This is the default implementation. Architecture
+ * implementations can override this.
+ */
+void __weak pcibios_penalize_isa_irq(int irq, int active) {}
+
 static void do_pci_disable_device(struct pci_dev *dev)
 {
 	u16 pci_command;