drm/bridge: fix documentation for the hdmi_audio_prepare() callback

Fix c&p error and change linuxdoc comment for the hdmi_audio_prepare()
callback from drm_bridge_funcs to mention the callback name instead of
the original prepare() callback.

Fixes: 0beba3f ("drm/bridge: connector: add support for HDMI codec framework")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20250106174645.463927e0@canb.auug.org.au/
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250107-drm-bridge-fix-docs-v1-1-84e539e6f348@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Author: lumag

include/drm/drm_bridge.h

@@ -691,7 +691,7 @@ struct drm_bridge_funcs {
 				  struct drm_bridge *bridge);
 
 	/**
-	 * @prepare:
+	 * @hdmi_audio_prepare:
 	 * Configures HDMI-encoder for audio stream. Can be called multiple
 	 * times for each setup. Mandatory if HDMI audio is enabled in the
 	 * bridge's configuration.