ALSA: mips: avoid potential uninitialized variable use
MIPS allmodconfig results in this warning:
sound/mips/hal2.c: In function 'hal2_gain_get':
sound/mips/hal2.c:224:35: error: 'r' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c:223:35: error: 'l' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c: In function 'hal2_gain_put':
sound/mips/hal2.c:260:13: error: 'new' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c:260:13: error: 'old' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Returning an error for all unexpected cases shuts up the warning