pci: auto: Reduce bridge mem alignment boundary for boston

Boston has a very limited memory range for PCI controllers, where
1MB can't easily fit into it.

Make alignment boundary of PCI memory resource allocation a Kconfig
option and default to 0x10000 for boston.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/drivers/pci/pci_auto.c b/drivers/pci/pci_auto.c
index 90f8188..b2c76b2 100644
--- a/drivers/pci/pci_auto.c
+++ b/drivers/pci/pci_auto.c
@@ -372,8 +372,8 @@
 	dm_pci_write_config8(dev, PCI_SUBORDINATE_BUS, 0xff);
 
 	if (pci_mem) {
-		/* Round memory allocator to 1MB boundary */
-		pciauto_region_align(pci_mem, 0x100000);
+		/* Round memory allocator */
+		pciauto_region_align(pci_mem, CONFIG_PCI_BRIDGE_MEM_ALIGNMENT);
 
 		/*
 		 * Set up memory and I/O filter limits, assume 32-bit
@@ -387,8 +387,8 @@
 	}
 
 	if (pci_prefetch) {
-		/* Round memory allocator to 1MB boundary */
-		pciauto_region_align(pci_prefetch, 0x100000);
+		/* Round memory allocator */
+		pciauto_region_align(pci_prefetch, CONFIG_PCI_BRIDGE_MEM_ALIGNMENT);
 
 		/*
 		 * Set up memory and I/O filter limits, assume 32-bit
@@ -465,8 +465,8 @@
 	dm_pci_write_config8(dev, PCI_SUBORDINATE_BUS, sub_bus - dev_seq(ctlr));
 
 	if (pci_mem) {
-		/* Round memory allocator to 1MB boundary */
-		pciauto_region_align(pci_mem, 0x100000);
+		/* Round memory allocator */
+		pciauto_region_align(pci_mem, CONFIG_PCI_BRIDGE_MEM_ALIGNMENT);
 
 		dm_pci_write_config16(dev, PCI_MEMORY_LIMIT,
 				      ((pci_mem->bus_lower - 1) >> 16) &
@@ -480,8 +480,8 @@
 				     &prefechable_64);
 		prefechable_64 &= PCI_PREF_RANGE_TYPE_MASK;
 
-		/* Round memory allocator to 1MB boundary */
-		pciauto_region_align(pci_prefetch, 0x100000);
+		/* Round memory allocator */
+		pciauto_region_align(pci_prefetch, CONFIG_PCI_BRIDGE_MEM_ALIGNMENT);
 
 		dm_pci_write_config16(dev, PCI_PREF_MEMORY_LIMIT,
 				      (((pci_prefetch->bus_lower - 1) >> 16) &