ice: pass num_vfs to ice_set_per_vf_res()

We are planning to replace the simple array structure tracking VFs with
a hash table. This change will also remove the "num_alloc_vfs" variable.

Instead, new access functions to use the hash table as the source of
truth will be introduced. These will generally be equivalent to existing
checks, except during VF initialization.

Specifically, ice_set_per_vf_res() cannot use the hash table as it will
be operating prior to VF structures being inserted into the hash table.

Instead of using pf->num_alloc_vfs, simply pass the num_vfs value in
from the caller.

Note that a sub-function of ice_set_per_vf_res, ice_determine_res, also
implicitly depends on pf->num_alloc_vfs. Replace ice_determine_res with
a simpler inline implementation based on rounddown_pow_of_two. Note that
we must explicitly check that the argument is non-zero since it does not
play well with zero as a value.

Instead of using the function and while loop, simply calculate the
number of queues we have available by dividing by num_vfs. Check if the
desired queues are available. If not, round down to the nearest power of
2 that fits within our available queues.

This matches the behavior of ice_determine_res but is easier to follow
as simple in-line logic. Remove ice_determine_res entirely.

With this change, we no longer depend on the pf->num_alloc_vfs during
the initialization phase of VFs. This will allow us to safely remove it
in a future planned refactor of the VF data structures.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>