Return error-code for failing interface

Rather than returning the error code for UART1 regardless of which
interface had problems, we should return the error code for the
interface that actually had an error.

Pretty sure this was a simple copy-paste mistake.

Author: sam-bristow

source/c_uart.c

@@ -46,13 +46,13 @@ BBIO_err uart_cleanup(void)
     if (e1 != BBIO_OK)
         return e1;
     if (e2 != BBIO_OK)
-        return e1;
+        return e2;
     if (e3 != BBIO_OK)
-        return e1;
+        return e3;
     if (e4 != BBIO_OK)
-        return e1;
+        return e4;
     if (e5 != BBIO_OK)
-        return e1;
+        return e5;
 
     return BBIO_OK;
 }