rpi-update doesn't properly detect if you're running with initramfs

[solskogen]

On a system that is running with initramfs:
root@raspberrypi:~# vcgencmd get_config ramfsfile ramfsfile= root@raspberrypi:~# uname -a Linux raspberrypi 6.6.51+rpt-rpi-2712 #1 SMP PREEMPT Debian 1:6.6.51-1+rpt3 (2024-10-08) aarch64 GNU/Linux