qlcnic: Convert vmalloc/memset to kcalloc

vmalloc is a limited resource.  Don't use it unnecessarily.

It seems this allocation should work with kcalloc.

Remove unnecessary memset(,0,) of buf as it's completely
overwritten as the previously only unset field in
struct qlcnic_pci_func_cfg is now set to 0.

Use kfree instead of vfree.
Use ETH_ALEN instead of 6.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>