KVM: SVM: Allocate IOPM pages after initial setup in svm_hardware_setup()

KVM: SVM: Allocate IOPM pages after initial setup in svm_hardware_setup()

Allocate pages for the IOPM after initial setup has been completed in
svm_hardware_setup(), so that sanity checks can be added in the setup flow
without needing to free the IOPM pages.  The IOPM is only referenced (via
iopm_base) in init_vmcb() and svm_hardware_unsetup(), so there's no need
to allocate it early on.

No functional change intended (beyond the obvious ordering differences,
e.g. if the allocation fails).

Link: https://lore.kernel.org/r/20250610225737.156318-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>