ARM: tegra: only select MACH_HAS_SND_SOC_TEGRA_WM8903 if SND_SOC

This fixes:
	warning: (MACH_HARMONY && MACH_KAEN && MACH_SEABOARD) selects MACH_HAS_SND_SOC_TEGRA_WM8903 which has unmet direct dependencies (SOUND && !M68K && SND && SND_SOC)

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-By: Colin Cross <ccross@android.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>