sandbox: pci: Move pci_offset_to_barnum() to pci.h

This function is useful in PCI emulators. More it into the header file to
avoid duplicating it in other drivers.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/misc/swap_case.c b/drivers/misc/swap_case.c
index 18d756e..75fe641 100644
--- a/drivers/misc/swap_case.c
+++ b/drivers/misc/swap_case.c
@@ -24,9 +24,6 @@
 	u32 bar[6];
 };
 
-#define offset_to_barnum(offset)	\
-		(((offset) - PCI_BASE_ADDRESS_0) / sizeof(u32))
-
 enum {
 	MEM_TEXT_SIZE	= 0x100,
 };
@@ -144,7 +141,7 @@
 		int barnum;
 		u32 *bar, result;
 
-		barnum = offset_to_barnum(offset);
+		barnum = pci_offset_to_barnum(offset);
 		bar = &plat->bar[barnum];
 
 		result = *bar;
@@ -224,7 +221,7 @@
 		int barnum;
 		u32 *bar;
 
-		barnum = offset_to_barnum(offset);
+		barnum = pci_offset_to_barnum(offset);
 		bar = &plat->bar[barnum];
 
 		debug("w bar %d=%lx\n", barnum, value);