his patch mainly fixes the huge delay when we ping from the RDC device to another...

his patch mainly fixes the huge delay when we ping from the RDC device to another host (160-230 ms).
r6040_rx() was rewritten.
Further changes:
- fix a bug in hex2str(), which overwrote the source with a zero
- removed rx_free_desc counter; allocate skb inside r6040_rx() on the fly
- r6040_rx: don't take the error from the MLSR register (may be too late) but from the descriptor (we may have to allow these errors (via MCR0) there
- r6040_alloc_rxbufs() may fail due to lack of skb, added a return value
- changed some debugs
- more defines
- version: 0.18 -> 0.19

Signed-Off by Joerg Albert <jal2@gmx.de>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@11508 3c298f89-4303-0410-b956-a3cf2f4a3e73