ibmvnic: merge ibmvnic_reset_init and ibmvnic_init

These two functions share the majority of the code, hence merge
them together. In the meanwhile, add a reset pass-in parameter
to differentiate them. Thus, the code is easier to read and to tell
the difference between reset_init and regular init.

Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>