doc: usb: usbmisc-imx: add imx7d compatible string

Add compatible string for imx7d-usbmisc.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
1 file changed