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 <jan.kiszka@siemens.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>