[minor] Tax id of supplier not fetching in purchase invoice (#12052)

erpnext/accounts/doctype/purchase_invoice/purchase_invoice.json

@@ -147,7 +147,7 @@
    "collapsible": 0, 
    "columns": 0, 
    "fieldname": "tax_id", 
-   "fieldtype": "Data", 
+   "fieldtype": "Read Only", 
    "hidden": 0, 
    "ignore_user_permissions": 0, 
    "ignore_xss_filter": 0, 
@@ -158,6 +158,7 @@
    "label": "Tax Id", 
    "length": 0, 
    "no_copy": 0, 
+   "options": "supplier.tax_id", 
    "permlevel": 0, 
    "precision": "", 
    "print_hide": 1, 
@@ -3913,7 +3914,7 @@
  "istable": 0, 
  "max_attachments": 0, 
  "menu_index": 0, 
- "modified": "2017-12-07 15:37:30.173811", 
+ "modified": "2017-12-15 17:49:51.230092", 
  "modified_by": "Administrator", 
  "module": "Accounts", 
  "name": "Purchase Invoice",