platform: set default bmc_platform
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 <3dfaff8fa6ae977f042064a112a6aac576279b9b@gmail.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

qemu/skiboot,open-power/skiboot,shenki/skiboot,mikey/skiboot,legoater/skiboot,stewart-ibm/skiboot,open-power/skiboot,shenki/skiboot,mikey/skiboot,mikey/skiboot,legoater/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,legoater/skiboot,shenki/skiboot,open-power/skiboot,open-power/skiboot,open-power/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,stewart-ibm/skiboot