platform: set default bmc_platform

The bmc_platform pointer is set to NULL by default and on non-AMI BMC
platforms. As a result a few places in hw/ipmi/ipmi-sel.c will blindly
dereference a NULL pointer.

This patch sets the default value for bmc_platform to generic_bmc to
avoid this.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

core/platform.c

@@ -28,7 +28,6 @@
 
 bool manufacturing_mode = false;
 struct platform	platform;
-const struct bmc_platform *bmc_platform = NULL;
 
 DEFINE_LOG_ENTRY(OPAL_RC_ABNORMAL_REBOOT, OPAL_PLATFORM_ERR_EVT, OPAL_CEC,
 		 OPAL_CEC_HARDWARE, OPAL_PREDICTIVE_ERR_FAULT_RECTIFY_REBOOT,
@@ -143,10 +142,15 @@ static struct platform generic_platform = {
 	.cec_power_down	= generic_cec_power_down,
 };
 
+const struct bmc_platform *bmc_platform = &generic_bmc;
+
 void set_bmc_platform(const struct bmc_platform *bmc)
 {
 	if (bmc)
 		prlog(PR_NOTICE, "PLAT: Detected BMC platform %s\n", bmc->name);
+	else
+		bmc = &generic_bmc;
+
 	bmc_platform = bmc;
 }