Configure MMC over GPIO microSD card by default

[gardners]

Something like:

root@OpenWrt:/# uci set mmc_over_gpio.@mmc_over_gpio[0].enabled=1
root@OpenWrt:/# uci set mmc_over_gpio.@mmc_over_gpio[0].DI_pin=18
root@OpenWrt:/# uci set mmc_over_gpio.@mmc_over_gpio[0].DO_pin=20
root@OpenWrt:/# uci set mmc_over_gpio.@mmc_over_gpio[0].CLK_pin=19
root@OpenWrt:/# uci set mmc_over_gpio.@mmc_over_gpio[0].CS_pin=23
root@OpenWrt:/# uci commit mmc_over_gpio
root@OpenWrt:/# /etc/init.d/mmc_over_gpio enable
etc/init.d/mmc_over_gpio start
root@OpenWrt:/# /etc/init.d/mmc_over_gpio start
configfs on /config type configfs (rw,relatime)
root@OpenWrt:/# [ 507.750000] gpio-mmc: Failed to request mmc_spi module.
[ 507.750000] mmc_spi spi32766.0: ASSUMING 3.2-3.4 V slot power
[ 510.790000] mmc_spi spi32766.0: setup: unsupported mode bits 4
[ 510.790000] mmc_spi spi32766.0: can't change chip-select polarity
[ 510.820000] mmc_spi spi32766.0: SD/MMC host mmc0, no DMA, no WP, no poweroff
[ 510.820000] gpio-mmc: MMC-Card "default" attached to GPIO pins di=18, do=20, clk=19, cs=23
[ 511.000000] mmc0: host does not support reading read-only switch, assuming write-enable
[ 511.010000] mmc0: new SDHC card on SPI
[ 511.020000] mmcblk0: mmc0:0000 USDU1 14.9 GiB
[ 511.050000] mmcblk0: p1

Then also add it to /etc/fstab.