Converting s32 functions to regular int in the previous patch of the series
caused triggering smatch warnings about missing error code.

New smatch warnings:
drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c:2884 ixgbe_get_lcd_t_x550em() warn: missing error code? 'status'
drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c:3130 ixgbe_enter_lplu_t_x550em() warn: missing error code? 'status'

Old smatch warnings:
drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c:2890 ixgbe_get_lcd_t_x550em() warn: missing error code? 'status'

Fix it by clearly stating returning error code as 0.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202401041701.6QKTsZmx-lkp@intel.com/Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>