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>

drivers/clk/sunxi-ng/ccu_mmc_timing.c

@@ -10,11 +10,11 @@
 #include "ccu_common.h"
 
 /**
- * sunxi_ccu_set_mmc_timing_mode: Configure the MMC clock timing mode
+ * sunxi_ccu_set_mmc_timing_mode - Configure the MMC clock timing mode
  * @clk: clock to be configured
  * @new_mode: true for new timing mode introduced in A83T and later
  *
- * Returns 0 on success, -ENOTSUPP if the clock does not support
+ * Return: %0 on success, %-ENOTSUPP if the clock does not support
  * switching modes.
  */
 int sunxi_ccu_set_mmc_timing_mode(struct clk *clk, bool new_mode)
@@ -46,8 +46,8 @@ EXPORT_SYMBOL_GPL(sunxi_ccu_set_mmc_timing_mode);
  * sunxi_ccu_set_mmc_timing_mode: Get the current MMC clock timing mode
  * @clk: clock to query
  *
- * Returns 0 if the clock is in old timing mode, > 0 if it is in
- * new timing mode, and -ENOTSUPP if the clock does not support
+ * Return: %0 if the clock is in old timing mode, > %0 if it is in
+ * new timing mode, and %-ENOTSUPP if the clock does not support
  * this function.
  */
 int sunxi_ccu_get_mmc_timing_mode(struct clk *clk)