hw/arm: sabrelite: Connect SPI flash CS line to GPIO3_19

hw/arm: sabrelite: Connect SPI flash CS line to GPIO3_19

The Linux spi-imx driver does not work on QEMU. The reason is that the
state of m25p80 loops in STATE_READING_DATA state after receiving
RDSR command, the new command is ignored. Before sending a new command,
CS line should be pulled high to make the state of m25p80 back to IDLE.

Currently the SPI flash CS line is connected to the SPI controller, but
on the real board, it's connected to GPIO3_19. This matches the ecspi1
device node in the board dts.

ecspi1 node in imx6qdl-sabrelite.dtsi:
  &ecspi1 {
          cs-gpios = <&gpio3 19 GPIO_ACTIVE_LOW>;
          pinctrl-names = "default";
          pinctrl-0 = <&pinctrl_ecspi1>;
          status = "okay";

          flash: m25p80@0 {
                  compatible = "sst,sst25vf016b", "jedec,spi-nor";
                  spi-max-frequency = <20000000>;
                  reg = <0>;
          };
  };

Should connect the SSI_GPIO_CS to GPIO3_19 when adding a spi-nor to
spi1 on sabrelite machine.

Verified this patch on Linux v5.14.

Logs:
  # echo "01234567899876543210" > test
  # mtd_debug erase /dev/mtd0 0x0 0x1000
  Erased 4096 bytes from address 0x00000000 in flash
  # mtd_debug write /dev/mtdblock0 0x0 20 test
  Copied 20 bytes from test to address 0x00000000 in flash
  # mtd_debug read /dev/mtdblock0 0x0 20 test_out
  Copied 20 bytes from address 0x00000000 in flash to test_out
  # cat test_out
  01234567899876543210#

Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210927142825.491-1-xchengl.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>