net/mlx5: Use del_timer_sync in fw reset flow of halting poll

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

net/mlx5: Use del_timer_sync in fw reset flow of halting poll

Substitute del_timer() with del_timer_sync() in fw reset polling

deactivation flow, in order to prevent a race condition which occurs

when del_timer() is called and timer is deactivated while another

process is handling the timer interrupt. A situation that led to

the following call trace:

RIP: 0010:run_timer_softirq+0x137/0x420

<IRQ>

recalibrate_cpu_khz+0x10/0x10

ktime_get+0x3e/0xa0

? sched_clock_cpu+0xb/0xc0

__do_softirq+0xf5/0x2ea

irq_exit_rcu+0xc1/0xf0

sysvec_apic_timer_interrupt+0x9e/0xc0

asm_sysvec_apic_timer_interrupt+0x12/0x20

</IRQ>