drivers/uart8250mem: Check for zero base address

Before adding a new UART to the coreboot/lb table, verify that it
has a non-zero base address.  This is consistent with all other
functions that use the uart_platform_base() function.

This was tested on google/kahlee by using an invalid UART number
and forcing the base address to 0.  Execution was able to complete
through depthcharge and into the OS.

Change-Id: I6d8183a461f0fedc254bf88de5ec96629a2a80ef
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/21996
Reviewed-by: Lijian Zhao <lijian.zhao@intel.com>
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed