idpf: Fix kernel-doc descriptions to avoid warnings

idpf: Fix kernel-doc descriptions to avoid warnings

In many functions the Return section is missing. Fix kernel-doc
descriptions to address that and other warnings.

Before the change:

$ scripts/kernel-doc -none -Wreturn drivers/net/ethernet/intel/idpf/idpf_txrx.c 2>&1 | wc -l
85

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>