ibmvnic: Split initialization of scrqs to its own routine

Split the sending of capability request crqs and the initialization
of sub crqs into their own routines. This is a first step to moving
the allocation of sub-crqs out of interrupt context.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>