fix(pm_low_power_modes): Remove unimplemented entry to LPM

Documenting ways to enter low power modes that are not implemented is
unnecessary and can be confusing to users. Remove the unimplemented
features and add them back when they are implemented.

Signed-off-by: Kendall Willis <k-willis@ti.com>

Author: kwillis01

source/linux/Foundational_Components/Power_Management/pm_low_power_modes.rst

@@ -59,18 +59,7 @@ overlay is loaded. Please refer to :ref:`How to enable DT overlays<howto_dt_over
 
 After Linux boots, the MCAN wakeup for Partial I/O is enabled.
 
-.. rubric:: To enable UART wakeup:
-
-.. code-block:: console
-
-   root@<machine>:~# echo enabled > /sys/class/tty/ttyS0/device/power/wakeup
-
-.. note::
-
-   UART wakeup from Partial I/O is currently being debugged on the EVM.
-
-With at least one of the wakeup sources enabled, Partial I/O mode can be
-entered with the following command:
+Partial I/O mode can be entered with the following command:
 
 .. code-block:: console
 
@@ -323,27 +312,6 @@ To enter MCU Only mode, set :code:`100 msec` resume latency for CPU0 in Linux:
 
    root@<machine>:~# echo 100000 > /sys/devices/system/cpu/cpu0/power/pm_qos_resume_latency_us
 
-.. important::
-
-   Note that the step below to set "enabled" won't work for current SDK
-   and will be supported in future release
-
-.. ifconfig:: CONFIG_part_variant in ('AM62X')
-
-   To enter MCU Only mode, enable MCU M4 core as a wakeup source in linux:
-
-   .. code-block:: console
-
-      root@am62xx-evm:~# echo enabled > /sys/bus/platform/devices/5000000.m4fss/power/wakeup
-
-.. ifconfig:: CONFIG_part_variant in ('AM62AX', 'AM62PX')
-
-   To enter MCU Only mode, enable MCU R5 core as a wakeup source in linux:
-
-   .. code-block:: console
-
-      root@<machine>:~# echo enabled > /sys/bus/platform/devices/79000000.r5f/power/wakeup
-
 Now, the SoC can be suspended using the following command:
 
 .. code-block:: console