Log: libstonithd: Drop crm_perror() in st_lha.c

The only thing we lose here is writing the message to stderr for CLI
tools. However, CLI tools have verbose options. It doesn't seem worth
passing pcmk__output_t down the call chain... which would be even more
of a pain since it would have to go in the stonith_t private data
somehow.

Other errors in this file already simply use crm_err().

Ref T172

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>