r300: remove lock.h link

diff --git a/src/mesa/drivers/dri/r300/radeon_lock.h b/src/mesa/drivers/dri/r300/radeon_lock.h
deleted file mode 120000 (symlink)
index 64bdf94..0000000
--- a/src/mesa/drivers/dri/r300/radeon_lock.h
+++ /dev/null
@@ -1 +0,0 @@
-../radeon/radeon_lock.h
\ No newline at end of file