Use dcr_host_t.base in dcr_unmap()

With the base stored in dcr_host_t, there's no need for callers to pass
the dcr_n into dcr_unmap(). In fact this removes the possibility of them
passing the incorrect value, which would then be iounmap()'ed.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/arch/powerpc/sysdev/dcr.c b/arch/powerpc/sysdev/dcr.c
index ab11c0b..427027c 100644
--- a/arch/powerpc/sysdev/dcr.c
+++ b/arch/powerpc/sysdev/dcr.c
@@ -126,13 +126,13 @@
 }
 EXPORT_SYMBOL_GPL(dcr_map);
 
-void dcr_unmap(dcr_host_t host, unsigned int dcr_n, unsigned int dcr_c)
+void dcr_unmap(dcr_host_t host, unsigned int dcr_c)
 {
 	dcr_host_t h = host;
 
 	if (h.token == NULL)
 		return;
-	h.token += dcr_n * h.stride;
+	h.token += host.base * h.stride;
 	iounmap(h.token);
 	h.token = NULL;
 }