vmstate: move VMSTATE_PCIE_AER_ERRS to hw/hw.h

vmstate: move VMSTATE_PCIE_AER_ERRS to hw/hw.h

VMSTATE_PCIE_AER_ERRS is indeed useful for other emulation drivers.
Move it to hw/hw.h under the name of VMSTATE_STRUCT_VARRAY_POINTER_UINT16.
Also add VMSTATE_STRUCT_VARRAY_POINTER_INT32 which is more or less
the same as _UINT16 macro, except the fact it uses int32_t internally.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Andrzej Zaborowski <andrew.zaborowski@intel.com>