Fix GCC v10 --with-openssl build after commit 030a9b3 (#935)

Fix GCC v10 --with-openssl build after commit 030a9b3 (#935)

    bio.cc:377:18: warning: unused variable 'ssl' [-Wunused-variable]

I removed the whole "we have a valid TLS connection" condition because
the code in question no longer uses the TLS connection object, and the
condition itself may change _after_ this code runs. The condition is
important to higher-level code (that calls the code that uses
allowSplice/allowBump state set in the affected low-level BIO method),
but there are many such conditions on that code path; there is no good
reason to single out this specific condition in this low-level code.