tracing/osnoise: Fix slab-out-of-bounds in _parse_integer_limit()

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

tracing/osnoise: Fix slab-out-of-bounds in _parse_integer_limit()

When config osnoise cpus by write() syscall, the following KASAN splat may
be observed:

BUG: KASAN: slab-out-of-bounds in _parse_integer_limit+0x103/0x130
Read of size 1 at addr ffff88810121e3a1 by task test/447
CPU: 1 UID: 0 PID: 447 Comm: test Not tainted 6.17.0-rc6-dirty #288 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x55/0x70
print_report+0xcb/0x610
kasan_report+0xb8/0xf0
_parse_integer_limit+0x103/0x130
bitmap_parselist+0x16d/0x6f0
osnoise_cpus_write+0x116/0x2d0
vfs_write+0x21e/0xcc0
ksys_write+0xee/0x1c0
do_syscall_64+0xa8/0x2a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>

This issue can be reproduced by below code:

const char *cpulist = "1";
int fd=open("/sys/kernel/debug/tracing/osnoise/cpus", O_WRONLY);
write(fd, cpulist, strlen(cpulist));

Function bitmap_parselist() was called to parse cpulist, it require that
the parameter 'buf' must be terminated with a '\0' or '\n'. Fix this issue
by adding a '\0' to 'buf' in osnoise_cpus_write().