mmc: sdhci-pic32: remove owner assignment

A platform_driver does not need to set an owner, it will be populated
by the driver core.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>