ARM: shmobile: Remove obsolete twd_local_timer declaration

The last user of twd_local_timer was removed in commit c99cd90d


("ARM: shmobile: r8a7779: Remove legacy SoC code").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>