ARM: imx: fix function type for CLK_OF_DECLARE

Adding function type checking to CLK_OF_DECLARE found a type mismatch with
mx35_clocks_init_dt. The function should return void.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Shawn Guo <shawn.guo@freescale.com>
Cc: Sascha Hauer <kernel@pengutronix.de>