clocksource: Fix type confusion for clocksource_mmio_readX_Y
The types' definations are:
o cycle_t -> u64
o readl_relaxed -> u32
o readw_relaxed -> u16
So let clocksource_mmio_readX_Ys return a cast to cycle_t, though
this maybe look reduntant sometimes, it make sense and they will be
more readable and less confusion...
This patch clarifies the functions type and fix it.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>