davinci: DA850/OMAP-L138 EVM: get rid of DA850_UI_EXP config option

Get rid of DA850_UI_EXP config option since it is not used anywhere
else in code.

Instead make the UI expander choice menu dependent on the EVM
selection itself.

Also add help text indicating that UI board is actually detected
automatically.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/Kconfig

@@ -130,22 +130,18 @@ config MACH_DAVINCI_DA850_EVM
 	bool "TI DA850/OMAP-L138 Reference Platform"
 	default ARCH_DAVINCI_DA850
 	depends on ARCH_DAVINCI_DA850
-	help
-	  Say Y here to select the TI DA850/OMAP-L138 Evaluation Module.
-
-config DA850_UI_EXP
-	bool "DA850/OMAP-L138 UI (User Interface) board expander configuration"
-	depends on MACH_DAVINCI_DA850_EVM
 	select GPIO_PCA953X
 	help
-	  Say Y here if you have the DA850/OMAP-L138 UI
-	  (User Interface) board installed and you want to
-	  enable the peripherals located on User Interface
-	  board contorlled by TCA6416 expander.
+	  Say Y here to select the TI DA850/OMAP-L138 Evaluation Module.
 
 choice
 	prompt "Select peripherals connected to expander on UI board"
-	depends on DA850_UI_EXP
+	depends on MACH_DAVINCI_DA850_EVM
+	help
+	  The presence of User Interface (UI) card on the DA850/OMAP-L138
+	  EVM is detected automatically based on successful probe of the I2C
+	  based GPIO expander on that card. This option selected in this
+	  menu has an effect only in case of a successful UI card detection.
 
 config DA850_UI_NONE
 	bool "No peripheral is enabled"