ASoC: pxa: select SND_PXA2XX_LIB for drivers that depend on it

Commit d767d3ce ("ASoC: pxa: provide PCM ops for ssp, i2s and ac97
components") created a build-time dependency to SND_PXA2XX_LIB but
missed to reflect that in Kconfig.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/pxa/Kconfig

@@ -24,15 +24,18 @@ config SND_PXA2XX_AC97
 config SND_PXA2XX_SOC_AC97
 	tristate
 	select AC97_BUS
+	select SND_PXA2XX_LIB
 	select SND_PXA2XX_LIB_AC97
 	select SND_SOC_AC97_BUS
 
 config SND_PXA2XX_SOC_I2S
+	select SND_PXA2XX_LIB
 	tristate
 
 config SND_PXA_SOC_SSP
 	tristate "Soc Audio via PXA2xx/PXA3xx SSP ports"
 	select PXA_SSP
+	select SND_PXA2XX_LIB
 
 config SND_MMP_SOC_SSPA
 	tristate