ASoC: omap: enable sound support on n900 on devicetree-based boot

With device tree, it is possible (and encouraged) to build N900
kernels without CONFIG_MACH_NOKIA_RX51. Update config file to enable
the driver build in this case.

This makes sound work on my n900 under 3.18-rc1.
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/omap/Kconfig

@@ -25,15 +25,15 @@ config SND_OMAP_SOC_N810
 	  Say Y if you want to add support for SoC audio on Nokia N810.
 
 config SND_OMAP_SOC_RX51
-	tristate "SoC Audio support for Nokia RX-51"
-	depends on SND_OMAP_SOC && ARM && (MACH_NOKIA_RX51 || COMPILE_TEST) && I2C
+	tristate "SoC Audio support for Nokia N900 (RX-51)"
+	depends on SND_OMAP_SOC && ARM && I2C
 	select SND_OMAP_SOC_MCBSP
 	select SND_SOC_TLV320AIC3X
 	select SND_SOC_TPA6130A2
 	depends on GPIOLIB
 	help
-	  Say Y if you want to add support for SoC audio on Nokia RX-51
-	  hardware. This is also known as Nokia N900 product.
+	  Say Y if you want to add support for SoC audio on Nokia N900
+	  cellphone.
 
 config SND_OMAP_SOC_AMS_DELTA
 	tristate "SoC Audio support for Amstrad E3 (Delta) videophone"