dpll: spec: use proper enum for pin capabilities attribute

BugLink: https://bugs.launchpad.net/bugs/2060097

[ Upstream commit 5c497a64820ef9f10962a9c37607df45d6395fa5 ]

The enum is defined, however the pin capabilities attribute does
refer to it. Add this missing enum field.

This fixes ynl cli output:

Example current output:
$ sudo ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/dpll.yaml --do pin-get --json '{"id": 0}'
{'capabilities': 4,
 ...
Example new output:
$ sudo ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/dpll.yaml --do pin-get --json '{"id": 0}'
{'capabilities': {'state-can-change'},
 ...

Fixes: 3badff3a25 ("dpll: spec: Add Netlink spec in YAML")
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20240306120739.1447621-1-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit cfad6598c4c916fb9236a3d85384f999f91e7026)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

Documentation/netlink/specs/dpll.yaml

@@ -274,6 +274,7 @@ attribute-sets:
       -
         name: capabilities
         type: u32
+        enum: pin-capabilities
       -
         name: parent-device
         type: nest