When building the UBI NVMEM provider on 32-bit platforms a compiler
warning is triggered due to different sizeof(int).
Fix this by using integer types with well-defined size.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Similar to supporting nvmem-layouts on MTD devices, also allow referencing
UBI and MMC devices in DT.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>