clk: rockchip: protect the pclk_usb_grf as critical on px30

Make this clock a real critical clock, so that writes to the usbphy grf
always succeed.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Link: https://lore.kernel.org/r/20190917081903.25139-5-heiko@sntech.de

drivers/clk/rockchip/clk-px30.c

@@ -799,7 +799,7 @@ static struct rockchip_clk_branch px30_clk_branches[] __initdata = {
 	GATE(0, "pclk_ddrphy", "pclk_top_pre", CLK_IGNORE_UNUSED, PX30_CLKGATE_CON(16), 3, GFLAGS),
 	GATE(PCLK_MIPIDSIPHY, "pclk_mipidsiphy", "pclk_top_pre", 0, PX30_CLKGATE_CON(16), 4, GFLAGS),
 	GATE(PCLK_MIPICSIPHY, "pclk_mipicsiphy", "pclk_top_pre", 0, PX30_CLKGATE_CON(16), 5, GFLAGS),
-	GATE(PCLK_USB_GRF, "pclk_usb_grf", "pclk_top_pre", CLK_IGNORE_UNUSED, PX30_CLKGATE_CON(16), 6, GFLAGS),
+	GATE(PCLK_USB_GRF, "pclk_usb_grf", "pclk_top_pre", 0, PX30_CLKGATE_CON(16), 6, GFLAGS),
 	GATE(0, "pclk_cpu_hoost", "pclk_top_pre", CLK_IGNORE_UNUSED, PX30_CLKGATE_CON(16), 7, GFLAGS),
 
 	/* PD_VI */
@@ -995,6 +995,7 @@ static const char *const px30_cru_critical_clocks[] __initconst = {
 	"usb480m",
 	"clk_uart2",
 	"pclk_uart2",
+	"pclk_usb_grf",
 };
 
 static void __init px30_clk_init(struct device_node *np)