Fix soft-reboot to support secure boot enabled platforms

[vivekrnv]

What I did

1. soft-reboot is failing on platforms with Secure boot enabled

root@sn-5400:/home/admin# soft-reboot
kexec unload failed: Permission denied
kexec_load failed: Permission denied
entry       = 0x86eff7760 flags = 0x3e0000
nr_segments = 7
segment[0].buf   = 0x556cb2a1ad30
segment[0].bufsz = 0x70
segment[0].mem   = 0x100000
segment[0].memsz = 0x1000
segment[1].buf   = 0x556cb2a22d70
segment[1].bufsz = 0x168
segment[1].mem   = 0x101000
segment[1].memsz = 0x1000
segment[2].buf   = 0x556cb2a1b320
segment[2].bufsz = 0x30
segment[2].mem   = 0x102000
segment[2].memsz = 0x1000
segment[3].buf   = 0x7f0b3655e010
segment[3].bufsz = 0x1fcf164
segment[3].mem   = 0x868c30000
segment[3].memsz = 0x1fd0000
segment[4].buf   = 0x7f0b38532210
segment[4].bufsz = 0x7b7418
segment[4].mem   = 0x86ac00000
segment[4].memsz = 0x438c000
segment[5].buf   = 0x556cb2a151c0
segment[5].bufsz = 0x4422
segment[5].mem   = 0x86eff2000
segment[5].memsz = 0x5000
segment[6].buf   = 0x556cb2a0df10
segment[6].bufsz = 0x70e0
segment[6].mem   = 0x86eff7000
segment[6].memsz = 0x9000
Watchdog armed for 180 seconds
Nothing has been loaded!

2. Use mokutil instead of bootctl as bootctl is not installed in Bookworm

How I did it

How to verify it

After fixing the scripts

root@sn5600:/home/admin# soft-reboot
+ SECURE_UPGRADE_ENABLED=1
+ [[ CHECK_SECURE_UPGRADE_ENABLED -ne 0 ]]
+ load_kernel_secure
+ invoke_kexec -s
packet_write_wait: port 22: Broken pipe

admin@sn5600:~$ show reboot-cause
User issued 'soft-reboot' command [User: admin, Time: Tue Jul 23 11:06:43 PM UTC 2024]

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[vivekrnv]

@davidpil2002 please review