drm/xe/guc: Drop error messages about missing GuC logs

The GuC log snapshot code would complain loudly if there was no GuC
log to take a snapshot of or if the snapshot alloc failed. Originally,
this code was only called on demand when a user (or developer)
explicitly requested a dump of the log. Hence an error message was
useful.

However, it is now part of the general devcoredump file and is called
for any GPU hang. Most people don't care about GuC logs and GPU hangs
do not generally mean a kernel/GuC bug. More importantly, there are
valid situations where there is no GuC log, e.g. SRIOV VFs.

So drop the error message.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3958


Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250113194405.2033085-1-John.C.Harrison@Intel.com