clocksource: sh_cmt: 32-bit control register support

Add support for CMT hardware with 32-bit control and counter
registers, as found on r8a73a4 and r8a7790. To use the CMT
with 32-bit hardware a second I/O memory resource needs to
point out the CMSTR register and it needs to be 32 bit wide.

Signed-off-by: Magnus Damm <damm@opensource.se>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>