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/Kconfig b/drivers/pci/Kconfig
index 8d02ab8..289d1de 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -75,6 +75,15 @@
 	  This should only be required on MIPS where CFG_SYS_SDRAM_BASE is still
 	  being used as virtual address.
 
+config PCI_BRIDGE_MEM_ALIGNMENT
+	hex "Alignment boundary of PCI memory resource allocation"
+	default 0x10000 if TARGET_BOSTON
+	default 0x100000
+	help
+	  Specify a boundary for alignment of PCI memory resource allocation,
+	  this is normally 0x100000 (1MB) but can be reduced to accommodate
+	  hardware with tight bridge range if hardware allows.
+
 config PCI_SRIOV
 	bool "Enable Single Root I/O Virtualization support for PCI"
 	help