Rework RAM disk driver to be configured using devicetree and
support multiple instances.
This patch also removes a copy of the RAM disk driver,
tests/subsys/fs/fat_fs_dual_drive/src/disk_access_test_drv.c,
that was there for testing multiple disk drivers support.
Bonus: one SYS_INIT() less and a memory region can be exported to the
host.
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
The files disk_access_usdhc.c, disk_access_spi_sdhc.c,
disk_access_stm32_sdmmc.c, disk_access_ram.c and
disk_access_flash.c are actually drivers for block devices and SD/MMC
controllers. This patch moves this drivers to drivers/disk and
reworks the configuration so that the drivers are selected when
the corresponding node is enabled.
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
