Sub: correct boot on boards with features missing

parameters don't exist for defaulting, so config error loop is entered.  The config error loop also isn't working well this early in the boot, so the board is not perfectly informative.

Config Error: param deflt fail:BARO_PROBE_EXT
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Config Error: param deflt fail:BARO_PROBE_EXT
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Config Error: param deflt fail:BARO_PROBE_EXT
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ArduSub/Parameters.h

@@ -382,9 +382,11 @@ static const struct AP_Param::defaults_table_struct defaults_table[] = {
     { "RC3_TRIM",            1100},
     { "COMPASS_OFFS_MAX",    1000},
     { "INS_GYR_CAL",         0},
+#if HAL_MOUNT_ENABLED
     { "MNT1_TYPE",           1},
     { "MNT1_DEFLT_MODE",     MAV_MOUNT_MODE_RC_TARGETING},
     { "MNT1_RC_RATE",        30},
+#endif
     { "RC7_OPTION",          214},   // MOUNT1_YAW
     { "RC8_OPTION",          213},   // MOUNT1_PITCH
     { "MOT_PWM_MIN",         1100},
@@ -395,7 +397,9 @@ static const struct AP_Param::defaults_table_struct defaults_table[] = {
     { "PSC_VELXY_P",         6.0f},
     { "EK3_SRC1_VELZ",       0},
 #if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_NAVIGATOR
+#if AP_BARO_PROBE_EXT_PARAMETER_ENABLED
     { "BARO_PROBE_EXT",      0},
+#endif
     { "BATT_MONITOR",        4},
     { "BATT_CAPACITY",       0},
     { "LEAK1_PIN",           27},
@@ -405,7 +409,9 @@ static const struct AP_Param::defaults_table_struct defaults_table[] = {
     { "SERVO16_FUNCTION",    7},     // k_mount_tilt
     { "SERVO16_REVERSED",    1},
 #else
+#if AP_BARO_PROBE_EXT_PARAMETER_ENABLED
     { "BARO_PROBE_EXT",      768},
+#endif
     { "SERVO9_FUNCTION",     59},    // k_rcin9, lights 1
     { "SERVO10_FUNCTION",    7},     // k_mount_tilt
 #endif