tools/lguest: Fix redefinition of struct virtio_pci_cfg_cap

Ours uses a u32 for the data, since we ensure it's always
aligned and it's x86 so it doesn't matter anyway.

  lguest.c:128:8: error: redefinition of ‘struct virtio_pci_cfg_cap’

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 3121bb02 ("virtio: define virtio_pci_cfg_cap in header.")
Signed-off-by: Ingo Molnar <mingo@kernel.org>