fsl-ls1028a-mnt-reform2_defconfig: add loglevel=7 workaround to ${bootargs}
the functionality of the dwc3 module depends on the loglevel
- loglevel=3 makes usb not work
- loglevel=7 makes usb work most of the time
https://community.mnt.re/t/no-keyboard-input-with-ls1028-board-and-latest-image/1994/13