staging: rtl8188eu: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix multiple
warnings by explicitly adding multiple break statements instead
of just letting the code fall through to the next case.

Link: https://github.com/KSPP/linux/issues/115


Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210528200650.GA39289@embeddedor


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