We can now enable CARDEMU_SECOND_UART in owhw/board.h, as it no
longer interferes with operation of the first port (USIM1). Whether
the second port actuall works still remains to be tested at this point.
This way the application on the USB host can control whether the
emulator should emulate that the card be inserted or not. We change the
reset-default back to 'not inserted' (GPIO output 0) and wait for the
application to explicitly request this by issuing
CEMU_USB_MSGT_DT_CARDINSERT.
