xilinx_ethlite: fix eth_can_rx() for ping-pong

The eth_can_rx() function only checks the first buffers status ("ping"). The
controller should be able to receive into "pong" when ping-pong is enabled.
Checks the active buffer (either "ping" or "pong") when determining can_rx()
rather than just testing "ping".

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
xilinx_ethlite: Flush queued packets on SW service

Software services a received packet by clearing the CTRL_S bit in the RX_CTRLn
register. If this bit is cleared, flush any packets queued for the device.

Reported-by: John Williams <john.williams@xilinx.com>
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
m25p80.c: Return state to IDLE after COLLECTING

Default to moving back to the IDLE state after the COLLECTING_DATA
state. For a well behaved guest this patch has no consequence, but
A bad guest could crash QEMU by using one of the erase commands
followed by a longer than 5 byte argument (undefined behaviour).

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
xilinx_ethlite: Avoid build warnings in debug code

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>