x86/ACPI: correct off-by-1 in SGI MMCFG check

As supported by the printk() (deliberately made visible in context by
also correcting a mis-indented return statement), "above 4GiB" is meant
here. Avoid comparison with a constant to "escape" Misra rule 7.2
complaints. (Note however that even up-to-date Linux, which is where we
"inherited" this code from, still uses the very same off-by-1 check.)

Fixes: 94ea0622c5 ("x86-64/mmcfg: relax base address restriction")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>

xen/arch/x86/x86_64/acpi_mmcfg.c

@@ -50,7 +50,7 @@ static int __init acpi_mcfg_check_entry(struct acpi_table_mcfg *mcfg,
 {
     int year;
 
-    if (cfg->address < 0xFFFFFFFF)
+    if (cfg->address == (uint32_t)cfg->address)
         return 0;
 
     if (!strncmp(mcfg->header.oem_id, "SGI", 3))
@@ -59,7 +59,7 @@ static int __init acpi_mcfg_check_entry(struct acpi_table_mcfg *mcfg,
     if (mcfg->header.revision >= 1 &&
         dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) &&
         year >= 2010)
-            return 0;
+        return 0;
 
     printk(KERN_ERR "MCFG region for %04x:%02x-%02x at %#"PRIx64
                     " (above 4GB) ignored\n",