ftrace: Do not read-verify buffer_size_kb value

[cloehle]

The sysfs documentation mentions that the value written to buffer_size_kb ftrace field may be rounded up. So skip the verify loop on this field.

The case we are worried about, a requested buffer size that the target cannot fulfill is caught anyway, as the sysfs write returns with an error that is caught.

[douglas-raillard-arm]

@marcbonnici note that we started encountering this on recent mainline kernels, so we cannot use the FtraceCollector on them at the moment without that fix

[cloehle]

Thanks! FYI the change making that necessary was commit 6d98a0f2ac3c ("tracing: Set actual size after ring buffer resize")