dsp: adsp-loader: Support dynamic size for array priv->adsp_fw_name.

Current implementation allocates fixed size for array priv->adsp_fw_name
but this may result in out of bound access if source adsp_fw_name_array
dts property size exceed this fixed size. This patch fixes this issue by
allocating priv->adsp_fw_name array with dynamic size of source array.
Also fixes bytes copied in strlcpy.

Change-Id: Iea031952224672c34eb7245996687985e18ef8be
Signed-off-by: Ajit Pandey <ajitp@codeaurora.org>