net: ethernet: ti: cpsw_ale: Remove unused accessor functions

W=1 builds flag that some accessor functions for ALE fields are unused.

Address this by splitting up the macros used to define these
accessors to allow only those that are used to be declared.

The warnings are verbose, but for example, the mcast_state case is
flagged by clang-18 as:

.../cpsw_ale.c:220:1: warning: unused function 'cpsw_ale_get_mcast_state' [-Wunused-function]
  220 | DEFINE_ALE_FIELD(mcast_state,           62,     2)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.../cpsw_ale.c:145:19: note: expanded from macro 'DEFINE_ALE_FIELD'
  145 | static inline int cpsw_ale_get_##name(u32 *ale_entry)                   \
      |                   ^~~~~~~~~~~~~~~~~~~
<scratch space>:196:1: note: expanded from here
  196 | cpsw_ale_get_mcast_state
      | ^~~~~~~~~~~~~~~~~~~~~~~~

Compile tested only.
No functional change intended.

Signed-off-by: Simon Horman <horms@kernel.org>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>