s390x/pci: fixup trap_msix()

The function trap_msix() is to check if pcistg instruction would access
msix table entries. The correct boundary condition should be
[table_offset, table_offset+entries*entry_size). But the current
condition calculated misses the last entry. So let's fixup it.

Acked-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Message-Id: <1503907487-2764-2-git-send-email-zyimin@linux.vnet.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Cornelia Huck <cohuck@redhat.com>