vmm: remove cmdline_addr from KernelConfig
vmm: remove cmdline_addr from KernelConfig

There is no sense in keeping that in memory
inside the KernelConfig since we can obtain it
from the x86_64 layout pretty easily.

Signed-off-by: Diana Popa <4240422768c1b315e51818a074064501037757cd@amazon.com>

firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker