update-linux-headers.sh: Don't hard code list of architectures

update-linux-headers.sh: Don't hard code list of architectures

Rather than hardcoding the list of architectures in the kernel
header update script, just import headers for every architecture
which supports KVM (with a blacklist exception for ia64 which
has KVM headers but is dead). This reduces the number of QEMU
files which need to be updated to add support for a new KVM
architecture.

Acked-by: Jan Kiszka <[email protected]>
Signed-off-by: Peter Maydell <[email protected]>
Signed-off-by: Marcelo Tosatti <[email protected]>