sysfs: constify bin_attribute argument of bin_attribute::read/write()

sysfs: constify bin_attribute argument of bin_attribute::read/write()

All callback implementers have been moved to the const variant of the
callbacks. The signature of the original callbacks can now be changed.
Also remove the now unnecessary transition machinery inside __BIN_ATTR().

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-1-96284e1e88ce@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>