drm/xe/eustall: Fix a possible pointer dereference after free

drm/xe/eustall: Fix a possible pointer dereference after free

If devm_add_action_or_reset() isn't successful, xe_eu_stall_fini()
is invoked. So, unsuccessful return from devm_add_action_or_reset()
shouldn't dereference gt->eu_stall as xe_eu_stall_fini() already
frees it. Fix this issue.

Fixes: 9a0b11d4cf3b ("drm/xe/eustall: Add support to init, enable and disable EU stall sampling")
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/eae49a414a7314921108e0388810aaee6261ad92.1741800396.git.harish.chegondi@intel.com
(cherry picked from commit 278469ff569e1082d56b4a7af26fbaecef9fbf3b)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>