sh: Remove Kconfig entries for TMU, CMT and MTU2

Now when drivers/clocksource/Kconfig has been
updated with entires for CMT, TMU and MTU2
it is safe to remove these from SH.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Wolfram Sang <wsa@sang-engineering.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>