fw-path-provider.c is only consumed by qdev-fw.c, which itself
is in softmmu_ss[], so we can restrict fw-path-provider.c to
softmmu too.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201207220709.4017938-1-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>