netkvm: Set m_nReusedRxBuffersLimit after all RX buffers are allocated

If allocation of all RX buffers fails then NetMaxReceiveBuffers will be decreased accordingly, however m_nReusedRxBuffersLimit will remain set as it is configured in NetKVM device settings.

For example, if Init.MaxRxBuffers is configured to 1024 and rx_queue_size is set 256, it may cause a VM to lose connectivity when all RX buffers are exhausted.

Signed-off-by: Sergey Bykov <sergey.bykov@nutanix.com>