Fix broken link of HIP reference

## Motivation

Fixes broken references in the HIP Doxygen documentation.

## Technical Details

Updates the references.

## JIRA ID

n/a

## Test Plan

n/a

## Test Result

n/a

## Submission Checklist

- [X] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

Signed-off-by: Jan Stephan <jan.stephan@amd.com>
[rocm-systems] ROCm/rocm-systems#4418 (commit 454af2f)

Author: j-stephan

docs/reference/hip_runtime_api_reference.rst

@@ -51,7 +51,7 @@ Global defines, enums, structs and files
 
 The structs, define macros, enums and files in the HIP runtime API.
 
-* :ref:`global_enum_defines_reference`
-* :ref:`driver_types_reference`
+* :doc:`Global enum and defines <../../doxygen/html/group___global_defs>`
+* :doc:`Driver types <../../doxygen/html/group___driver_types>`
 * :doc:`../../doxygen/html/annotated`
 * :doc:`../../doxygen/html/files`