sysmobts: add missing break statement in l1if_handle_ind()
sysmobts: add missing break statement in l1if_handle_ind()

this was introduced in 21b020b33633683d7c785af15c773aab0f79d0de and
luckily spotted by coverity (CID 1347446)

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts