mfd: core: Make platform_data pointer const in struct mfd_cell

The content of the platform_data of a struct mfd_cell is simply passed on
to the platform_device_add_data() call in mfd_add_device() .

platform_device_add_data() already handles the data behind that pointer
as const and also uses kmemdup to create a copy of the data before
handing that copy over to the newly created platform-device,
so there is no reason to not extend this to struct mfd_cell, as the old
copy in the mfd_cell will be stale anyway.

This allows to pass structs gathered from of_device_get_match_data()
as platform-data to sub-devices - which is retrieved as const already.

Signed-off-by: Heiko Stuebner <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

include/linux/mfd/core.h

···
 	int			(*resume)(struct platform_device *dev);
 
 	/* platform data passed to the sub devices drivers */
-	void			*platform_data;
+	const void		*platform_data;
 	size_t			pdata_size;
 
 	/* Matches ACPI */