echo all command characters entered on serial console

This is required to make python pexpect.fdexpect happy, as it
requires that all characters are echo-ed back in order to detect
when the output of a given command starts.

Change-Id: I73b24e43f6c8b86a2766aba67d8307c184448aa0

firmware/apps/cardem/main.c

@@ -108,6 +108,8 @@ static void check_exec_dbg_cmd(void)
 		return;
 
 	ch = UART_GetChar();
+	/* We must echo the character to make python fdexpect happy, whcih we use in factory testing */
+	fputc(ch, stdout);
 
 	board_exec_dbg_cmd(ch);
 }