ASoC: rt1015: Remove unnecessary const

ASoC: rt1015: Remove unnecessary const

Clang warns:

../sound/soc/codecs/rt1015.c:392:14: warning: duplicate 'const'
declaration specifier [-Wduplicate-decl-specifier]
static const SOC_ENUM_SINGLE_DECL(rt1015_boost_mode_enum, 0, 0,
             ^
../include/sound/soc.h:355:2: note: expanded from macro
'SOC_ENUM_SINGLE_DECL'
        SOC_ENUM_DOUBLE_DECL(name, xreg, xshift, xshift, xtexts)
        ^
../include/sound/soc.h:352:2: note: expanded from macro
'SOC_ENUM_DOUBLE_DECL'
        const struct soc_enum name = SOC_ENUM_DOUBLE(xreg, xshift_l, xshift_r, \
        ^
1 warning generated.

Remove the const after static to fix it.

Fixes: df31007400c3 ("ASoC: rt1015: add rt1015 amplifier driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/845
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20200124155750.33753-1-natechancellor@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>