ar71xx: kernel: enable PCI on QCA9556 SoC

This patch enables the PCI bus on the QCA9556 SoC, the same way it is
done on the same family SoC QCA9558.

Tested on a MikroTik RouterBoard wAPG-5HacT2HnD (wAP AC).

Signed-off-by: Roger Pueyo Centelles <roger.pueyo@guifi.net>

target/linux/ar71xx/patches-4.4/741-MIPS-ath79-add-PCI-for-QCA9556-SoC.patch

@@ -0,0 +1,12 @@
+--- a/arch/mips/ath79/pci.c
++++ b/arch/mips/ath79/pci.c
+@@ -324,7 +324,8 @@ int __init ath79_register_pci(void)
+						 QCA953X_PCI_MEM_SIZE,
+						 0,
+						 ATH79_IP2_IRQ(0));
+-	} else if (soc_is_qca9558()) {
++	} else if (soc_is_qca9558() ||
++		   soc_is_qca9556()) {
+		pdev = ath79_register_pci_ar724x(0,
+						 QCA955X_PCI_CFG_BASE0,
+						 QCA955X_PCI_CTRL_BASE0,

target/linux/ar71xx/patches-4.9/741-MIPS-ath79-add-PCI-for-QCA9556-SoC.patch

@@ -0,0 +1,12 @@
+--- a/arch/mips/ath79/pci.c
++++ b/arch/mips/ath79/pci.c
+@@ -324,7 +324,8 @@ int __init ath79_register_pci(void)
+						 QCA953X_PCI_MEM_SIZE,
+						 0,
+						 ATH79_IP2_IRQ(0));
+-	} else if (soc_is_qca9558()) {
++	} else if (soc_is_qca9558() ||
++		   soc_is_qca9556()) {
+		pdev = ath79_register_pci_ar724x(0,
+						 QCA955X_PCI_CFG_BASE0,
+						 QCA955X_PCI_CTRL_BASE0,