clk: imx31: fix rewritten input argument of mx31_clocks_init()

Function mx31_clocks_init() is called during clock intialization on
legacy boards with reference clock frequency passed as its input
argument, this can be verified by examination of the function
declaration found in arch/arm/mach-imx/common.h and actual function
users which include that header file.

Inside CCF driver the function ignores its input argument, by chance
the used value in the function body is the same as input arguments on
side of all callers.

Fixes: d9388c84 ("clk: imx31: Do not call mxc_timer_init twice when booting with DT")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>