ICH9 SMB: make TYPE_ICH9_SMB_DEVICE macro public

ICH9 SMB: make TYPE_ICH9_SMB_DEVICE macro public

ICH9 SMB bridge can be created using qdev API despite existence of helper
function. The type name is needed for such creation. Using a preprocessor
alias instead the string type name itself is preferable.

The patch makes the alias accessible through the header.

Signed-off-by: Efimov Vasily <real@ispras.ru>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>