ASoC: Intel: Add help text for SND_SOC_INTEL_SST_TOPLEVEL

Symbol SND_SOC_INTEL_SST_TOPLEVEL is user selectable so add the
help text for this symbol.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/Kconfig

@@ -34,6 +34,11 @@ config SND_SOC_INTEL_SST_TOPLEVEL
 	depends on X86 || COMPILE_TEST
 	select SND_SOC_INTEL_MACH
 	select SND_SOC_INTEL_COMMON
+	help
+          Intel ASoC Audio Drivers. If you have a Intel machine that
+          has audio controller with a DSP and I2S or DMIC port, then
+          enable this option by saying Y or M
+          If unsure select "N".
 
 config SND_SOC_INTEL_HASWELL
 	tristate "Intel ASoC SST driver for Haswell/Broadwell"