drm/xe: Make xe_gt_freq part of the Documentation

The documentation was created with the creation of the component,
however it has never been actually shown in the actual Documentation.

While doing this, fixes the identation style, to avoid new warnings
while building htmldocs.

Fixes: bef52b5c7a ("drm/xe: Create a xe_gt_freq component for raw management and sysfs")
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250521165146.39616-3-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Documentation/gpu/xe/index.rst

@@ -16,6 +16,7 @@ DG2, etc is provided to prototype the driver.
    xe_migrate
    xe_cs
    xe_pm
+   xe_gt_freq
    xe_pcode
    xe_gt_mcr
    xe_wa

Documentation/gpu/xe/xe_gt_freq.rst

@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========================
+Xe GT Frequency Management
+==========================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_freq.c
+   :doc: Xe GT Frequency Management
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_freq.c
+   :internal:

drivers/gpu/drm/xe/xe_gt_freq.c

@@ -32,6 +32,7 @@
  * Xe's Freq provides a sysfs API for frequency management:
  *
  * device/tile#/gt#/freq0/<item>_freq *read-only* files:
+ *
  * - act_freq: The actual resolved frequency decided by PCODE.
  * - cur_freq: The current one requested by GuC PC to the PCODE.
  * - rpn_freq: The Render Performance (RP) N level, which is the minimal one.
@@ -39,6 +40,7 @@
  * - rp0_freq: The Render Performance (RP) 0 level, which is the maximum one.
  *
  * device/tile#/gt#/freq0/<item>_freq *read-write* files:
+ *
  * - min_freq: Min frequency request.
  * - max_freq: Max frequency request.
  *             If max <= min, then freq_min becomes a fixed frequency request.