ASoC: jz4740: Depend on MIPS instead of MACH_JZ4740

Depending on MACH_JZ4740 prevent us from creating a generic kernel that
works on more than one MIPS board. Instead, we just depend on MIPS being
set.
Signed-off-by: NPaul Cercueil <paul@crapouillou.net>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/jz4740/Kconfig

 config SND_JZ4740_SOC
 	tristate "SoC Audio for Ingenic JZ4740 SoC"
-	depends on MACH_JZ4740 || COMPILE_TEST
+	depends on MIPS || COMPILE_TEST
 	select SND_SOC_GENERIC_DMAENGINE_PCM
 	help
 	  Say Y or M if you want to add support for codecs attached to