building with W=2 has these errors
redundant redeclaration of ‘zd_rf_generic_patch_6m’ [-Werror=redundant-decls]
redundant redeclaration of ‘zd_rf_patch_6m_band_edge’ [-Werror=redundant-decls]

Remove the second decls.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230204200902.1709343-1-trix@redhat.com