[PATCH 3/3] mmc: meson-gx: improve meson_mmc_clk_set

Heiner Kallweit [off-list ref] writes:

The following changes are quite small, therefore I combined them in
one patch. If you'd prefer to separate the changes just let me know.

- ret doesn't need to be initialized with 0
- use standard !clk_rate notation to check for a zero value
- If clk_rate is zero we return here. Therefore all further checks
  in this function for clk_rate != 0 are not needed.
- switch from dev_warn to dev_err if the clock can't be set
- If due to clock source and available divider values the requested
  frequency isn't matched exactly (always the case if requested
  frequency is 52 MHz), then just print the differing values as
  debug message and not as warning.
- Also remove ret from the message as it is always 0.
- In the case of actual frequency not exactly matching the requested
  one set mmc->actual_clock to the requested frequency.
  So far mmc->actual_clock wasn't set at all in this case.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

All nice cleanup, thanks!

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>

Kevin