ice: Don't allow more channels than LAN MSI-X available

Currently users could create more channels than LAN MSI-X available.
This is happening because there is no check against pf->num_lan_msix
when checking the max allowed channels and will cause performance issues
if multiple Tx and Rx queues are tied to a single MSI-X. Fix this by not
allowing more channels than LAN MSI-X available in pf->num_lan_msix.

Fixes: 87324e74

 ("ice: Implement ethtool ops for channels")
Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>