devcoredump: Define 'struct bin_attribute' through macro

The macro saves some lines of code and simplifies the constification of
the attribute.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250114-sysfs-const-bin_attr-devcoredump-v1-1-fa93be30efae@weissschuh.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>