DONOTMERGE: Hack: Always disable MMC cache to avoid card becoming stuck.

DONOTMERGE: Hack: Always disable MMC cache to avoid card becoming stuck.

[    0.210673] mmc0: SDHCI controller on d4281000.mmc [d4281000.mmc] using ADMA
[    0.301489] mmc0: new DDR MMC card at address 0001
[    0.302156] mmcblk0: mmc0:0001 QNW00A 7.28 GiB
[    0.308976] mmcblk0boot0: mmc0:0001 QNW00A 4.00 MiB
[    0.310318] mmcblk0boot1: mmc0:0001 QNW00A 4.00 MiB
[    0.311571] mmcblk0rpmb: mmc0:0001 QNW00A 512 KiB, chardev (248:0)
[  171.353426] mmc0: Card stuck being busy! __mmc_poll_for_busy
[  171.353443] mmc0: cache flush error -110
[  201.399007] mmc0: Card stuck being busy! __mmc_poll_for_busy
[  201.399023] mmc0: cache flush error -110
[  231.415093] mmc0: Card stuck being busy! __mmc_poll_for_busy
[  231.415109] mmc0: cache flush error -110
[  261.464688] mmc0: Card stuck being busy! __mmc_poll_for_busy
[  261.464703] mmc0: cache flush error -110