ice: fix NULL pointer dereference in ice_unplug_aux_dev() on reset

In the Linux kernel, the following vulnerability has been resolved:

ice: fix NULL pointer dereference in ice_unplug_aux_dev() on reset

Issuing a reset when the driver is loaded without RDMA support, will results in a crash as it attempts to remove RDMA's non-existent auxbus device: echo 1 > /sys/class/net//device/reset

BUG: kernel NULL pointer dereference, address: 0000000000000008 ... RIP: 0010:ice_unplug_aux_dev+0x29/0x70 [ice] ... Call Trace:

ice_prepare_for_reset+0x77/0x260 [ice] pci_dev_save_and_disable+0x2c/0x70 pci_reset_function+0x88/0x130 reset_store+0x5a/0xa0 kernfs_fop_write_iter+0x15e/0x210 vfs_write+0x273/0x520 ksys_write+0x6b/0xe0 do_syscall_64+0x79/0x3b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e

ice_unplug_aux_dev() checks pf->cdev_info->adev for NULL pointer, but pf->cdev_info will also be NULL, leading to the deref in the trace above.

Introduce a flag to be set when the creation of the auxbus device is successful, to avoid multiple NULL pointer checks in ice_unplug_aux_dev().