add poweroff command

hc

2023-12-14 982b8cc116118b3463d3f332581945625722acd8

 kernel/arch/arm/mach-pxa/Makefile.boot
..
..
@@ -1,2 +1,3 @@
1
+# SPDX-License-Identifier: GPL-2.0-only
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2
    zreladdr-y	+= 0xa0008000
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3