ASoC: cs42l52: fix default value for MASTERA_VOL.

The default register value for MASTERA_VOL is 0x00, the same as
MASTERB_VOL.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Brian Austin <brian.austin@cirrus.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org