da850-evm: allow pca953x module build

Change the mach-davinci Kconfig file so that GPIO_PCA953X is default when
MACH_DAVINCI_DA850_EVM is set instead of always selecting. This allows users
to compile pca953x as a module.

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
CC: Sergei Shtylyov <sshtylyov@mvista.com>
CC: Nori, Sekhar <nsekhar@ti.com>
Reviewed-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/Kconfig

@@ -148,7 +148,6 @@ config MACH_DAVINCI_DA850_EVM
 	bool "TI DA850/OMAP-L138/AM18x Reference Platform"
 	default ARCH_DAVINCI_DA850
 	depends on ARCH_DAVINCI_DA850
-	select GPIO_PCA953X
 	help
 	  Say Y here to select the TI DA850/OMAP-L138/AM18x Evaluation Module.
 
@@ -178,6 +177,9 @@ config DA850_UI_RMII
 
 endchoice
 
+config GPIO_PCA953X
+	default MACH_DAVINCI_DA850_EVM
+
 config MACH_TNETV107X
 	bool "TI TNETV107X Reference Platform"
 	default ARCH_DAVINCI_TNETV107X