Rename _pexpect_spawn() to _pexpect_spawn_ipmi()
Rename _pexpect_spawn() to _pexpect_spawn_ipmi()

A new _pexpect_spawn() is added, to be used for general cases. It is
used by _pexpect_spawn_ipmi().

Signed-off-by: Zack Cerza <d7cdf09fc0f0426e98c9978ee42da5d61fa54986@redhat.com>

ktdreyer/teuthology,dmick/teuthology,ceph/teuthology,ktdreyer/teuthology,dmick/teuthology,dmick/teuthology,SUSE/teuthology,ceph/teuthology,SUSE/teuthology,SUSE/teuthology