Fix cppcheck warnings:

sound/atmel/ac97c.c:478:30: style: Clarify calculation precedence for
'&' and '?'. [clarifyCalculation]
    casr & AC97C_CSR_OVRUN   ? " OVRUN"   : "",
                             ^
sound/atmel/ac97c.c:479:30: style: Clarify calculation precedence for
'&' and '?'. [clarifyCalculation]
    casr & AC97C_CSR_RXRDY   ? " RXRDY"   : "",
                             ^
sound/atmel/ac97c.c:480:30: style: Clarify calculation precedence for
'&' and '?'. [clarifyCalculation]
    casr & AC97C_CSR_UNRUN   ? " UNRUN"   : "",
                             ^
sound/atmel/ac97c.c:481:30: style: Clarify calculation precedence for
'&' and '?'. [clarifyCalculation]
    casr & AC97C_CSR_TXEMPTY ? " TXEMPTY" : "",
                             ^
sound/atmel/ac97c.c:482:30: style: Clarify calculation precedence for
'&' and '?'. [clarifyCalculation]
    casr & AC97C_CSR_TXRDY   ? " TXRDY"   : "",
                             ^
sound/atmel/ac97c.c:524:30: style:...