prov/psm3: Convert error message to debug output

In pmodels/mpich#6518, a user reported seeing a "No HALs registered"
message when using MPICH+libfabric. The error is because the psm3
provider is not compatible with --disable-shared. MPICH will just ignore
the error and try to pick another provider, so we convert it to debug
output to avoid spamming the user.

Signed-off-by: Ken Raffenetti <[email protected]>

prov/psm3/psm3/psm2_hal.c

@@ -712,7 +712,7 @@ static struct _psmi_hal_instance *psm3_hal_get_pi_inst(void)
 		return psm3_hal_current_hal_instance;
 
 	if (!psm3_num_hal) {
-		_HFI_ERROR("No HALs registered\n");
+		_HFI_DBG("No HALs registered\n");
 		return NULL;
 	}