sanlock: Don't spam logs with "target pid not found"

sanlock: Don't spam logs with "target pid not found"

Commit v1.2.4-52-gda879e5 fixed issues with domains started before
sanlock driver was enabled by checking whether a running domain is
registered with sanlock and if it's not, sanlock driver is basically
ignored for the domain.

However, it was checking this even for domain which has just been
started and no sanlock_* API was called for them yet. This results in

    cmd 9 target pid 2135544 not found

error messages to appear in sanlock.log whenever we start a new domain.

This patch avoids this useless check for freshly started domains.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>