i3200_edac: Make a local function static

This local symbol is used only in this file.
Fix the following sparse warnings:

drivers/edac/i3200_edac.c:264:14: warning: symbol 'i3200_map_mchbar' was not declared. Should it be static?
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/i3200_edac.c

@@ -260,8 +260,7 @@ static void i3200_check(struct mem_ctl_info *mci)
 	i3200_process_error_info(mci, &info);
 }
 
-
-void __iomem *i3200_map_mchbar(struct pci_dev *pdev)
+static void __iomem *i3200_map_mchbar(struct pci_dev *pdev)
 {
 	union {
 		u64 mchbar;