staging cxt1e1: refactored ring buffer dump functions to avoid sparse warnings

Sparse spit out these warnings:

drivers/staging/cxt1e1/musycc.c:68:1: warning: context imbalance in 'musycc_dump_rxbuffer_ring' - different lock contexts for basic block
drivers/staging/cxt1e1/musycc.c:136:1: warning: context imbalance in 'musycc_dump_txbuffer_ring' - different lock contexts for basic block

The new functions musycc_dump_[rt]xbuffer_ring_locked() assume that the lock is
held. musycc_dump_[rt]xbuffer_ring() take the lock.

Signed-off-by: Wolfgang Ocker <weo@weo1.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>