hw/msic: imx6_ccm: Correct register value for silicon type

Currently when U-Boot boots, it prints "??" for i.MX processor:

  CPU:   Freescale i.MX?? rev1.0 at 792 MHz

The register that was used to determine the silicon type is
undocumented in the latest IMX6DQRM (Rev. 6, 05/2020), but we
can refer to get_cpu_rev() in arch/arm/mach-imx/mx6/soc.c in
the U-Boot source codes that USB_ANALOG_DIGPROG is used.

Update its reset value to indicate i.MX6Q.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20210106063504.10841-3-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/imx6_ccm.c

@@ -462,7 +462,7 @@ static void imx6_ccm_reset(DeviceState *dev)
     s->analog[USB_ANALOG_USB2_VBUS_DETECT] = 0x00000004;
     s->analog[USB_ANALOG_USB2_CHRG_DETECT] = 0x00000000;
     s->analog[USB_ANALOG_USB2_MISC] = 0x00000002;
-    s->analog[USB_ANALOG_DIGPROG] = 0x00000000;
+    s->analog[USB_ANALOG_DIGPROG] = 0x00630000;
 
     /* all PLLs need to be locked */
     s->analog[CCM_ANALOG_PLL_ARM]   |= CCM_ANALOG_PLL_LOCK;