MODULE_LICENSE expects "GPL v2", not "GPLv2"

... and we have few enough places using the latter to make it
simpler to do search and replace...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/sh/drivers/heartbeat.c b/arch/sh/drivers/heartbeat.c
index ab77b0e..938817e3 100644
--- a/arch/sh/drivers/heartbeat.c
+++ b/arch/sh/drivers/heartbeat.c
@@ -154,4 +154,4 @@
 
 MODULE_VERSION(DRV_VERSION);
 MODULE_AUTHOR("Paul Mundt");
-MODULE_LICENSE("GPLv2");
+MODULE_LICENSE("GPL v2");