PCI: keystone: Fix MSI code that retrieves struct pcie_port pointer

Commit cbce7900 ("PCI: designware: Make driver arch-agnostic") changed
the host bridge sysdata pointer from the ARM pci_sys_data to the DesignWare
pcie_port structure, and changed pcie-designware.c to reflect that.  But it
did not change the corresponding code in pci-keystone-dw.c, so it caused
crashes on Keystone:

  Unable to handle kernel NULL pointer dereference at virtual address 00000030
  pgd = c0003000
  [00000030] *pgd=80000800004003, *pmd=00000000
  Internal error: Oops: 206 [#1] PREEMPT SMP ARM
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.2-00139-gb74f926 #2
  Hardware name: Keystone
  PC is at ks_dw_pcie_msi_irq_unmask+0x24/0x58

Change pci-keystone-dw.c to expect sysdata to be the struct pcie_port
pointer.

[bhelgaas: changelog]
Fixes: cbce7900 ("PCI: designware: Make driver arch-agnostic")
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v4.4+
CC: Zhou Wang <wangzhou1@hisilicon.com>

drivers/pci/host/pci-keystone-dw.c

@@ -58,11 +58,6 @@
 
 #define to_keystone_pcie(x)	container_of(x, struct keystone_pcie, pp)
 
-static inline struct pcie_port *sys_to_pcie(struct pci_sys_data *sys)
-{
-	return sys->private_data;
-}
-
 static inline void update_reg_offset_bit_pos(u32 offset, u32 *reg_offset,
 					     u32 *bit_pos)
 {
@@ -108,7 +103,7 @@ static void ks_dw_pcie_msi_irq_ack(struct irq_data *d)
 	struct pcie_port *pp;
 
 	msi = irq_data_get_msi_desc(d);
-	pp = sys_to_pcie(msi_desc_to_pci_sysdata(msi));
+	pp = (struct pcie_port *) msi_desc_to_pci_sysdata(msi);
 	ks_pcie = to_keystone_pcie(pp);
 	offset = d->irq - irq_linear_revmap(pp->irq_domain, 0);
 	update_reg_offset_bit_pos(offset, &reg_offset, &bit_pos);
@@ -146,7 +141,7 @@ static void ks_dw_pcie_msi_irq_mask(struct irq_data *d)
 	u32 offset;
 
 	msi = irq_data_get_msi_desc(d);
-	pp = sys_to_pcie(msi_desc_to_pci_sysdata(msi));
+	pp = (struct pcie_port *) msi_desc_to_pci_sysdata(msi);
 	ks_pcie = to_keystone_pcie(pp);
 	offset = d->irq - irq_linear_revmap(pp->irq_domain, 0);
 
@@ -167,7 +162,7 @@ static void ks_dw_pcie_msi_irq_unmask(struct irq_data *d)
 	u32 offset;
 
 	msi = irq_data_get_msi_desc(d);
-	pp = sys_to_pcie(msi_desc_to_pci_sysdata(msi));
+	pp = (struct pcie_port *) msi_desc_to_pci_sysdata(msi);
 	ks_pcie = to_keystone_pcie(pp);
 	offset = d->irq - irq_linear_revmap(pp->irq_domain, 0);