ibmvnic: Fix completion structure initialization

ibmvnic: Fix completion structure initialization

Fix device initialization completion handling for vNIC adapters.
Initialize the completion structure on probe and reinitialize when needed.
This also fixes a race condition during kdump where the driver can attempt
to access the completion struct before it is initialized:

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc0000000081acbe0
Oops: Kernel access of bad area, sig: 11 [#1]
LE SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: ibmvnic(+) ibmveth sunrpc overlay squashfs loop
CPU: 19 PID: 301 Comm: systemd-udevd Not tainted 4.18.0-64.el8.ppc64le #1
NIP:  c0000000081acbe0 LR: c0000000081ad964 CTR: c0000000081ad900
REGS: c000000027f3f990 TRAP: 0300   Not tainted  (4.18.0-64.el8.ppc64le)
MSR:  800000010280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 28228288  XER: 00000006
CFAR: c000000008008934 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 1
GPR00: c0000000081ad964 c000000027f3fc10 c0000000095b5800 c0000000221b4e58
GPR04: 0000000000000003 0000000000000001 000049a086918581 00000000000000d4
GPR08: 0000000000000007 0000000000000000 ffffffffffffffe8 d0000000014dde28
GPR12: c0000000081ad900 c000000009a00c00 0000000000000001 0000000000000100
GPR16: 0000000000000038 0000000000000007 c0000000095e2230 0000000000000006
GPR20: 0000000000400140 0000000000000001 c00000000910c880 0000000000000000
GPR24: 0000000000000000 0000000000000006 0000000000000000 0000000000000003
GPR28: 0000000000000001 0000000000000001 c0000000221b4e60 c0000000221b4e58
NIP [c0000000081acbe0] __wake_up_locked+0x50/0x100
LR [c0000000081ad964] complete+0x64/0xa0
Call Trace:
[c000000027f3fc10] [c000000027f3fc60] 0xc000000027f3fc60 (unreliable)
[c000000027f3fc60] [c0000000081ad964] complete+0x64/0xa0
[c000000027f3fca0] [d0000000014dad58] ibmvnic_handle_crq+0xce0/0x1160 [ibmvnic]
[c000000027f3fd50] [d0000000014db270] ibmvnic_tasklet+0x98/0x130 [ibmvnic]
[c000000027f3fda0] [c00000000813f334] tasklet_action_common.isra.3+0xc4/0x1a0
[c000000027f3fe00] [c000000008cd13f4] __do_softirq+0x164/0x400
[c000000027f3fef0] [c00000000813ed64] irq_exit+0x184/0x1c0
[c000000027f3ff20] [c0000000080188e8] __do_irq+0xb8/0x210
[c000000027f3ff90] [c00000000802d0a4] call_do_irq+0x14/0x24
[c000000026a5b010] [c000000008018adc] do_IRQ+0x9c/0x130
[c000000026a5b060] [c000000008008ce4] hardware_interrupt_common+0x114/0x120

Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>