Quiets warnings like:
drivers/dahdi/dahdi-base.c:8494:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (chan->txstate != DAHDI_TXSTATE_OFFHOOK) break;
^
Needed since Linux 5.4 commit (a035d552a93bb9ef60487, "Makefile: Globally enable
fall-33bb9f2a0dc857ff869through warning") [1]
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a035d552a93bb9ef6048733bb9f2a0dc857
Signed-off-by: Shaun Ruffell <sruffell@sruffell.net>