Update API Spec for host mapping model changes

[joseph-v]

What this PR does / why we need it: Update API Spec for host mapping model changes. Following models are updated

1. MaskingView: Removed native_port_id from the model
2. StorageHostInitiator: Added type with enum values to Initiator model

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #814

Special notes for your reviewer:

Release note:

[codecov[bot]]

Codecov Report

Merging #815 (368698d) into master (122c928) will increase coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #815      +/-   ##
==========================================
+ Coverage   70.55%   70.57%   +0.01%     
==========================================
  Files         180      180              
  Lines       18648    18652       +4     
  Branches     2750     2750              
==========================================
+ Hits        13158    13163       +5     
  Misses       4646     4646              
+ Partials      844      843       -1     

Impacted Files	Coverage Δ
delfin/api/v1/storage_host_initiators.py	57.14% <ø> (ø)
delfin/drivers/fake_storage/__init__.py	93.95% <100.00%> (+0.31%)	:arrow_up: