fix some build warnings when using GCC 4.6.2:

arch/arm/mach-mx6/board-mx6q_sabresd.c:1588:20:
warning: function declaration isn't a prototype [-Wstrict-prototypes]

This patch also fix the following section mismatch warnings:
The function imx6q_init_audio() references
the variable __initconst imx6_imx_ssi_data.
This is often because imx6q_init_audio lacks a __initconst
annotation or the annotation of imx6_imx_ssi_data is wrong.

Signed-off-by: Jason Liu <r64343@freescale.com>