net: phy: micrel: Fixes FIELD_GET assertion

FIELD_GET() must only be used with a mask that is a compile-time
constant. Mark the functions as __always_inline to avoid the problem.

Fixes: 21b688da ("net: phy: micrel: Cable Diag feature for lan8814 phy")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Divya Koppera <Divya.Koppera@microchip.com>
Link: https://lore.kernel.org/r/20221011095437.12580-1-Divya.Koppera@microchip.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>