ACPI: Use resource_size() in osl.c

Use the resource_size() function instead of explicit computation.

[rjw: Subject and changelog]
Signed-off-by: Alexandru Gheorghiu <gheorghiuandru@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 586e7e9..4d31748 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1555,7 +1555,7 @@
 	else
 		space_id = ACPI_ADR_SPACE_SYSTEM_MEMORY;
 
-	length = res->end - res->start + 1;
+	length = resource_size(res);
 	if (acpi_enforce_resources != ENFORCE_RESOURCES_NO)
 		warn = 1;
 	clash = acpi_check_address_range(space_id, res->start, length, warn);