CVE-2024-27060 thunderbolt: Fix NULL pointer dereference in tb_port_update_credits()

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

thunderbolt: Fix NULL pointer dereference in tb_port_update_credits()

Olliver reported that his system crashes when plugging in Thunderbolt 1
device:

BUG: kernel NULL pointer dereference, address: 0000000000000020
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:tb_port_do_update_credits+0x1b/0x130 [thunderbolt]
Call Trace:
<TASK>
? __die+0x23/0x70
? page_fault_oops+0x171/0x4e0
? exc_page_fault+0x7f/0x180
? asm_exc_page_fault+0x26/0x30
? tb_port_do_update_credits+0x1b/0x130
? tb_switch_update_link_attributes+0x83/0xd0
tb_switch_add+0x7a2/0xfe0
tb_scan_port+0x236/0x6f0
tb_handle_hotplug+0x6db/0x900
process_one_work+0x171/0x340
worker_thread+0x27b/0x3a0
? __pfx_worker_thread+0x10/0x10
kthread+0xe5/0x120
? __pfx_kthread+0x10/0x10
ret_from_fork+0x31/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>

This is due the fact that some Thunderbolt 1 devices only have one lane
adapter. Fix this by checking for the lane 1 before we read its credits.