clk: remove a redundant header

The linux/err.h header file was included twice.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index c871ea6..cc9c430 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -12,7 +12,6 @@
 #include <linux/bitops.h>
 #include <linux/err.h>
 #include <clk-uclass.h>
-#include <linux/err.h>
 
 struct udevice;