drm/xe/xe_survivability: Simplify runtime survivability error handling

drm/xe/xe_survivability: Simplify runtime survivability error handling

xe_survivability_mode_runtime_enable() returns an int, but its caller
csc_hw_error_work() ignores the return value and cannot take any
meaningful recovery action on failure. The function logs errors via
dev_err() and proceeds to declare the device wedged regardless of
sysfs creation failure, making the return value redundant.

Change the return type to void and remove the unnecessary
error handling in the caller.

v2:
- Return is not require after the sysfs creation fail. (Rodrigo/Riana)
- Change int to void return type. (Rodrigo)
- Remove extra message from csc_hw_error_work().

v3:
- Remove ret variable. (Raag)

v4:
- Drop ret variable from other part of code.

v5:
- Reframe as refactoring instead of bug fix. (Raag)
- Remove Fixes tag and update subject line.

Signed-off-by: Mallesh Koujalagi <mallesh.koujalagi@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Link: https://patch.msgid.link/20260504110300.1467303-2-mallesh.koujalagi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>