NET:KS8695: add API for get rx interrupt bit

1. Add API Add k8695_get_rx_enable_bit() for get Rx interrupt
enable/status bit.
2. add some comment or document about some functions and variables.
3.  update driver version to "1.02"
4. add napi_enable() and napi_disable() in open/close file method.

Signed-off-by: Figo.zhang <figo1802@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>