arm: mxs: be more careful when enabling gpmi_clk

The data sheet says that the DIV field cannot change while the CLKGATE
bit is set or modified. So do it a little more carefully, by first
clearing the bit, waiting for that to appear, then setting the DIV
field.
Signed-off-by: NRasmus Villemoes <rasmus.villemoes@prevas.dk>

arch/arm/cpu/arm926ejs/mxs/mxs.c

@@ -103,8 +103,11 @@ int arch_cpu_init(void)
 		&clkctrl_regs->hw_clkctrl_clkseq_set);
 
 	/* Set GPMI clock to ref_xtal / 1 */
+	clrbits_le32(&clkctrl_regs->hw_clkctrl_gpmi, CLKCTRL_GPMI_CLKGATE);
+	while (readl(&clkctrl_regs->hw_clkctrl_gpmi) & CLKCTRL_GPMI_CLKGATE)
+		;
 	clrsetbits_le32(&clkctrl_regs->hw_clkctrl_gpmi,
-		CLKCTRL_GPMI_CLKGATE | CLKCTRL_GPMI_DIV_MASK, 1);
+		CLKCTRL_GPMI_DIV_MASK, 1);
 
 	udelay(1000);