CVE-2026-72309: tracing/remotes: Fix leak in trace_remote_alloc_buffer() error path

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

tracing/remotes: Fix leak in traceremoteallocbuffer() error path

If page allocation fails in traceremoteallocbuffer(), desc->nrcpus is not yet incremented for the current CPU. As a consequence, on error, half-allocated rbdesc will not be freed in traceremotefreebuffer().

Increment desc->nrcpus as soon as the first allocation for the current CPU has succeeded.