dahdi_dummy: Build failure with kernel >= 6.15.3

[mnhauke]

init_module(): Magic init_module() function name is deprecated, use module_init(fn) instead.

see
https://lore.kernel.org/all/366bfdbe92736cde9fb01d5d3eb9b98e9070a1ec.1742852846.git.jpoimboe@kernel.org/
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=4fab2d7628dd38f3fa8a5e615199350ecaeb17a8

build error

dahdi_dummy.o: error: objtool: init_module(): Magic init_module() function name is deprecated, use module_init(fn) instead
make[4]: *** [/usr/src/linux-6.15.5-1/scripts/Makefile.build:204: dahdi_dummy.o] Error 255