[PATCH] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[Markus Elfring]

…
> The IS_ERR() test in the return value check should be replaced with NULL test.
…

How do you think about to convert such a change description into
an imperative wording?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.12-rc3#n94

Regards,
Markus