ARM: shmobile: r8a7740: add TMU timer support

This patch enabled TMU0 timer on r8a7740.
But TMU1 timer is not supported yet

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>