fix(pm_low_power_modes): Remove false confirmation of DeepSleep

The PMIC_LPM_EN signal stays high when the device is in DeepSleep or MCU
Only. The documentation asserts that PMIC_LPM_EN is 0V when in these
modes, which is false.

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

Author: kwillis01

source/linux/Foundational_Components/Power_Management/pm_low_power_modes.rst

@@ -279,9 +279,6 @@ In order to enter Deep Sleep, use the following command:
       [  230.295457] psci: CPU3 killed (polled 0 ms)
 
 This partially indicates that Linux has finished it's Deep Sleep suspend sequence.
-For further confirmation, one can take a look at the PMIC_LPM_EN pin on the EVM
-(after programming the PMCTRL_SYS register (0x43018080) to 0x15). Here, if the pin is 3.3V when active and
-0V when in deep sleep.
 
 .. note::