mx5: Correct a warning in clock.c

This corects the warning below, obtained with my gcc 4.6 compiler.

arch/arm/cpu/armv7/mx5/libmx5.o: In function `decode_pll':
arch/arm/cpu/armv7/mx5/clock.c:94: undefined reference to `__aeabi_uldivmod'

I am not able to test this on MX5x hardware, but it does improve the
MAKEALL output for me. You may already have a similar patch, but I cannot
see it on the list.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/cpu/armv7/mx5/clock.c

@@ -91,7 +91,7 @@ static uint32_t decode_pll(struct mxc_pll_reg *pll, uint32_t infreq)
 	if (ctrl & MXC_DPLLC_CTL_DPDCK0_2_EN)
 		refclk *= 2;
 
-	refclk /= pdf + 1;
+	do_div(refclk, pdf + 1);
 	temp = refclk * mfn_abs;
 	do_div(temp, mfd + 1);
 	ret = refclk * mfi;