clk: sunxi-ng: fix ccu_mmc_timing.c kernel-doc issues

clk: sunxi-ng: fix ccu_mmc_timing.c kernel-doc issues

Use '-' to separate the function name and its description.
Use '%' on constants in kernel-doc notation.
Use the kernel-doc Return: format for function return values.

Fixes this warning:
ccu_mmc_timing.c:21: warning: No description found for return value of 'sunxi_ccu_set_mmc_timing_mode'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Samuel Holland <samuel@sholland.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sunxi@lists.linux.dev
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20221122184844.6794-1-rdunlap@infradead.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>