staging: dgnc: UART_IIR_XOFF code is buggy

The UART_IIR_XOFF was supposed to be a no-op but, because there was a
missing semi-colon, the if statement is not "Empty".  I have just deleted
this code because it was supposed to be a no-op anyway.  UART_IIR_XOFF
is a standard define and not something specific to this driver.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>