fix(linux): update LVGL demo performance issue

Add a note for LVGL demo to address the performnace issue
present for releases 11.02.08.02  and 12.00.00.07.04.

Signed-off-by: Mahammed Sadik Shaik <s-sadik@ti.com>

Author: sadik-smd

source/linux/Demo_User_Guides/TI_LVGL_Demo_User_Guide.rst

@@ -166,6 +166,15 @@ Launching the TI LVGL Demo
 
    #. Launch the demo by typing `/usr/bin/lvglsim` into the UART command prompt.
 
+.. ifconfig:: CONFIG_part_variant in ('AM62LX')
+
+   .. note::
+
+      **AM62LX Performance Issue - SDK 11.02.08.02  and 12.00.00.07.04:**
+
+      For AM62LX platform in SDK releases 11.02.08.02  and 12.00.00.07.04, the default LVGL application is configured to run on DRM
+      (Direct Rendering Manager) which has resulted in performance issues. To improve performance, the rendering mode
+      needs to be changed from DRM to FB (framebuffer) rendering.
 
 **********************
 Using the TI LVGL Demo