ACPICA: use acpi_size instead of u32 for prefix_path_length

strlen() returns a size_t, so use acpi_size instead of u32 for
prefix_path_length.

ACPICA commit 0f64c317e769a63679442404421da1d5bd61068a

Link: https://github.com/acpica/acpica/commit/0f64c317Signed-off-by: Sven Barth <sb@miray.de>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/nsnames.c

@@ -346,7 +346,7 @@ char *acpi_ns_build_prefixed_pathname(union acpi_generic_state *prefix_scope,
 	char *full_path = NULL;
 	char *external_path = NULL;
 	char *prefix_path = NULL;
-	u32 prefix_path_length = 0;
+	acpi_size prefix_path_length = 0;
 
 	/* If there is a prefix, get the pathname to it */