hwrng: bcm63xx - fix device tree compilation

Adds missing include that resulted in implicit device tree functions errors.

Fixes: 7b651706712b ("hwrng: bcm63xx - add device tree support")
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/bcm63xx-rng.c

@@ -12,6 +12,7 @@
 #include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/hw_random.h>
+#include <linux/of.h>
 
 #define RNG_CTRL			0x00
 #define RNG_EN				(1 << 0)