mmc: core: Remove stray CONFIG_EXPERIMENTAL dependencies

CONFIG_EXPERIMENTAL has been removed from the kernel, so clean
up its use in MMC_EMBEDDED_SDIO and MMC_PARANOID_SD_INIT options.

Change-Id: If414c265134b36740a84564274a631803c8e81b4
Cc: Arve Hjønnevåg <arve@android.com>
Cc: San Mehat <san@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Reported-by: Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>