clk: imx6ull: use OSC clock during AXI rate change

On i.MX6 ULL using PLL3 seems to cause a freeze when setting
the parent to IMX6UL_CLK_PLL3_USB_OTG. This only seems to appear
since commit 6f9575e5 ("clk: imx: Add CLK_IS_CRITICAL flag
for busy divider and busy mux"), probably because the clock is
now forced to be on.

Fixes: 6f9575e5("clk: imx: Add CLK_IS_CRITICAL flag for busy divider and busy mux")
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NStephen Boyd <sboyd@kernel.org>

drivers/clk/imx/clk-imx6ul.c

@@ -464,7 +464,7 @@ static void __init imx6ul_clocks_init(struct device_node *ccm_node)
 	clk_set_rate(clks[IMX6UL_CLK_AHB], 99000000);
 
 	/* Change periph_pre clock to pll2_bus to adjust AXI rate to 264MHz */
-	clk_set_parent(clks[IMX6UL_CLK_PERIPH_CLK2_SEL], clks[IMX6UL_CLK_PLL3_USB_OTG]);
+	clk_set_parent(clks[IMX6UL_CLK_PERIPH_CLK2_SEL], clks[IMX6UL_CLK_OSC]);
 	clk_set_parent(clks[IMX6UL_CLK_PERIPH], clks[IMX6UL_CLK_PERIPH_CLK2]);
 	clk_set_parent(clks[IMX6UL_CLK_PERIPH_PRE], clks[IMX6UL_CLK_PLL2_BUS]);
 	clk_set_parent(clks[IMX6UL_CLK_PERIPH], clks[IMX6UL_CLK_PERIPH_PRE]);