Are you on the imx_2.6.38_11.09.01 branch?
Hi Phil,
You'll probably need more patches as well, but try the following patch
diff --git a/arch/arm/mach-mx5/Kconfig b/arch/arm/mach-mx5/Kconfig
index 6d02118..a688c4b 100644
--- a/arch/arm/mach-mx5/Kconfig
+++ b/arch/arm/mach-mx5/Kconfig
@@ -41,6 +41,7 @@ config SOC_IMX53
bool
select MXC_TZIC
select ARCH_MXC_IOMUX_V3
+ select ARCH_MXC_AUDMUX_V2
select ARCH_HAS_CPUFREQ
select ARCH_MX53
select IMX_HAVE_PLATFORM_FEC