hw/misc: imx6_ccm: Update PMU_MISC0 reset value

hw/misc: imx6_ccm: Update PMU_MISC0 reset value

U-Boot expects PMU_MISC0 register bit 7 is set (see init_bandgap()
in arch/arm/mach-imx/mx6/soc.c) during boot. This bit indicates the
bandgap has stabilized.

With this change, the latest upstream U-Boot (v2021.01-rc3) for imx6
sabrelite board (mx6qsabrelite_defconfig), with a slight change made
by switching CONFIG_OF_SEPARATE to CONFIG_OF_EMBED, boots to U-Boot
shell on QEMU with the following command:

$ qemu-system-arm -M sabrelite -smp 4 -m 1G -kernel u-boot \
    -display none -serial null -serial stdio

Boot log below:

  U-Boot 2021.01-rc3 (Dec 12 2020 - 17:40:02 +0800)

  CPU:   Freescale i.MX?? rev1.0 at 792 MHz
  Reset cause: POR
  Model: Freescale i.MX6 Quad SABRE Lite Board
  Board: SABRE Lite
  I2C:   ready
  DRAM:  1 GiB
  force_idle_bus: sda=0 scl=0 sda.gp=0x5c scl.gp=0x55
  force_idle_bus: failed to clear bus, sda=0 scl=0
  force_idle_bus: sda=0 scl=0 sda.gp=0x6d scl.gp=0x6c
  force_idle_bus: failed to clear bus, sda=0 scl=0
  force_idle_bus: sda=0 scl=0 sda.gp=0xcb scl.gp=0x5
  force_idle_bus: failed to clear bus, sda=0 scl=0
  MMC:   FSL_SDHC: 0, FSL_SDHC: 1
  Loading Environment from MMC... *** Warning - No block device, using default environment

  In:    serial
  Out:   serial
  Err:   serial
  Net:   Board Net Initialization Failed
  No ethernet found.
  starting USB...
  Bus usb@2184000: usb dr_mode not found
  USB EHCI 1.00
  Bus usb@2184200: USB EHCI 1.00
  scanning bus usb@2184000 for devices... 1 USB Device(s) found
  scanning bus usb@2184200 for devices... 1 USB Device(s) found
         scanning usb for storage devices... 0 Storage Device(s) found
         scanning usb for ethernet devices... 0 Ethernet Device(s) found
  Hit any key to stop autoboot:  0
  =>

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20210106063504.10841-2-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>