[PATCH 4/5] mmc: use EXPORT_SYMBOL_GPL for mmc_detect_change

[Christoph Hellwig]

On Mon, Jul 31, 2023 at 10:38:05AM +0200, Christoph Hellwig wrote:
> mmc_detect_change is used via symbol_get, which was only ever intended
> for very internal symbols like this one.  Use EXPORT_SYMBOL_GPL
> for it so that symbol_get can enforce only being used on
> EXPORT_SYMBOL_GPL symbols.

Btw, I really wonder if this should actually be used through symbol_get.
It seems like the MIPS/alchemy boards should simply require MMC to be
built in and not modular, or the IRQ handlers should move into a driver.

That would be a much less mechanical change, but this use really looks
a bit odd.  And makes me wonder if we should only allow symbol_get
on symbols specifically marked to supported it, but that would be
another incremental step.