mfd: twl-core: Fix accessibility of some twl4030 audio registers

There are some unused registers in twl4030 at I2C address 0x49 and function
twl4030_49_nop_reg() is used to check accessibility of that registers. These
registers are written in decimal format but the values are correct in
hexadecimal format. (It can be checked few lines above the patched code -
these registers are marked as unused there.)

As a consequence three registers of audio submodule are treated as
inaccessible (preamplifier carkit right and both handsfree registers).

Cc: stable@vger.kernel.org
Signed-off-by: Tomas Novotny <tomas@novotny.cz>
Signed-off-by: Lee Jones <lee.jones@linaro.org>