ASoC: cht_bsw_rt5645: Fix writing to string literal

We cannot use strcpy() to write to a const char * location. This is
causing a 'BUG: unable to handle kernel paging request' error at boot
when using the cht-bsw-rt5645 driver.

With this patch we also fix a wrong indexing in the driver where the
codec_name of the wrong dai_link is being overwritten.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>