mmc: renesas_sdhi: remove manual clk handling

The SDHI driver en-/disabled its main clock on its own, e.g. during
probe() and remove(). Now, we leave all handling to RPM.

clk_summary before:
sd0                   1        1        0    12480000          0     0  50000
   sdif0              2        2        0    12480000          0     0  50000

clk_summary after:
sd0                   1        1        0    12480000          0     0  50000
   sdif0              1        1        0    12480000          0     0  50000

Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20200519164251.5430-1-wsa+renesas@sang-engineering.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>