netlink: specs: support unterminated-ok

ynl-gen-c.py supports check unterminated-ok, but the yaml schemas don't
have this key. Add this to the yaml files.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20240308081239.3281710-1-liuhangbin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/genetlink-c.yaml

@@ -209,6 +209,11 @@ properties:
                   exact-len:
                     description: Exact length for a string or a binary attribute.
                     $ref: '#/$defs/len-or-define'
+                  unterminated-ok:
+                    description: |
+                      For string attributes, do not check whether attribute
+                      contains the terminating null character.
+                    type: boolean
               sub-type: *attr-type
               display-hint: &display-hint
                 description: |

Documentation/netlink/genetlink-legacy.yaml

@@ -252,6 +252,11 @@ properties:
                   exact-len:
                     description: Exact length for a string or a binary attribute.
                     $ref: '#/$defs/len-or-define'
+                  unterminated-ok:
+                    description: |
+                      For string attributes, do not check whether attribute
+                      contains the terminating null character.
+                    type: boolean
               sub-type: *attr-type
               display-hint: *display-hint
               # Start genetlink-c

Documentation/netlink/netlink-raw.yaml

@@ -271,6 +271,11 @@ properties:
                   exact-len:
                     description: Exact length for a string or a binary attribute.
                     $ref: '#/$defs/len-or-define'
+                  unterminated-ok:
+                    description: |
+                      For string attributes, do not check whether attribute
+                      contains the terminating null character.
+                    type: boolean
               sub-type: *attr-type
               display-hint: *display-hint
               # Start genetlink-c