ARM: shmobile: sh73a0: remove DIV4_ZT* clocks

DIV4_ZT* clocks are for debugging and trace bus clock.
It is not necessary to control it from Linux/Software.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>