nl802154: fix some kernel-doc warnings

nl802154: fix some kernel-doc warnings

Correct multiple kernel-doc warnings in nl802154.h:

- Fix a typo on one enum name to avoid a kernel-doc warning.
- Drop 2 enum descriptions that are no longer needed.
- Mark 2 internal enums as "private:" so that kernel-doc is not needed
  for them.

Warning: nl802154.h:239 Enum value 'NL802154_CAP_ATTR_MAX_MAXBE' not described in enum 'nl802154_wpan_phy_capability_attr'
Warning: nl802154.h:239 Excess enum value '%NL802154_CAP_ATTR_MIN_CCA_ED_LEVEL' description in 'nl802154_wpan_phy_capability_attr'
Warning: nl802154.h:239 Excess enum value '%NL802154_CAP_ATTR_MAX_CCA_ED_LEVEL' description in 'nl802154_wpan_phy_capability_attr'
Warning: nl802154.h:369 Enum value '__NL802154_CCA_OPT_ATTR_AFTER_LAST' not described in enum 'nl802154_cca_opts'
Warning: nl802154.h:369 Enum value 'NL802154_CCA_OPT_ATTR_MAX' not described in enum 'nl802154_cca_opts'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251016035917.1148012-1-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>