i40e: use the safe hash table iterator when deleting mac filters

This patch replaces hash_for_each function with hash_for_each_safe
when calling  __i40e_del_filter. The hash_for_each_safe function is
the right one to use when iterating over a hash table to safely remove
a hash entry. Otherwise, incorrect values may be read from freed memory.

Detected by CoverityScan, CID 1402048 Read from pointer after free

Signed-off-by: Lihong Yang <lihong.yang@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>