ARM: dts: am335x: Enable PMIC shutdown controller for BeagleBone Blue

Enable ti,pmic-shutdown-controller property for BeagleBone Blue to allow
proper system shutdown. Without this property, the board does not shut down
completely - 3V3 rail stays powered and the power LED remains on, requiring
a manual reset button press to fully power off.

The property was previously deleted, but this causes incomplete shutdown as
reported in issue #68. The TPS65217 PMIC needs the shutdown-controller
property to properly sequence power-off and cut power to all rails.

With this change, the shutdown sequence works correctly:
- All USR LEDs turn off
- Power LED turns off
- 3V3 rail is powered down
- Board fully powers off without requiring reset button

This aligns BBBlue behavior with other BeagleBone variants that use
ti,pmic-shutdown-controller for proper power management.

Fixes: #68
Signed-off-by: immortal71 <newaashish190@gmail.com>

Author: immortal71

src/arm/ti/omap/am335x-boneblue.dts

@@ -362,8 +362,6 @@
 /include/ "../../tps65217.dtsi"
 
 &tps {
-	/delete-property/ ti,pmic-shutdown-controller;
-
 	charger {
 		interrupts = <0>, <1>;
 		interrupt-names = "USB", "AC";