module: Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN

module: Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN

The maximum module name length (MODULE_NAME_LEN) is somewhat confusingly
defined in terms of the maximum parameter prefix length
(MAX_PARAM_PREFIX_LEN), when in fact the dependency is in the opposite
direction.

This split originates from commit 730b69d22525 ("module: check kernel param
length at compile time, not runtime"). The code needed to use
MODULE_NAME_LEN in moduleparam.h, but because module.h requires
moduleparam.h, this created a circular dependency. It was resolved by
introducing MAX_PARAM_PREFIX_LEN in moduleparam.h and defining
MODULE_NAME_LEN in module.h in terms of MAX_PARAM_PREFIX_LEN.

Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN for clarity. This matches
the similar approach of defining MODULE_INFO in module.h and __MODULE_INFO
in moduleparam.h.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Link: https://lore.kernel.org/r/20250630143535.267745-6-petr.pavlu@suse.com
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>