can we use mandatory-y for non-uapi headers?

[Christoph Hellwig]

Hi Masahiro,

what is the reason that the documentation says mandatory-y should only
be used for uapi headers?  If would also be very useful for normal
asm-generic headers where most people use the generic version and we
only have a few overrides.  Two headers that immediately come to mind
are dma-mapping.h, or msi.h.