staging: gdm72xx: WIMAX_GDM72XX should depend on either USB or MMC

The gdm72xx driver needs to have either the USB or SDIO implementation
enabled to provide useful functionalities, so the driver should depend
on either USB or MMC. This patch makes WIMAX_GDM72XX depend on either
USB or MMC.

Also, WIMAX_GDM72XX needs to be built as a module if its dependent
interface, either USB or MMC, is built as a module. This patch enforces
that in the WIMAX_GDM72XX_USB and WIMAX_GDM72XX_SDIO dependency.
Reported-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NBen Chan <benchan@chromium.org>
Cc: Sage Ahn <syahn@gctsemi.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm72xx/Kconfig

@@ -4,7 +4,7 @@
 
 menuconfig WIMAX_GDM72XX
 	tristate "GCT GDM72xx WiMAX support"
-	depends on NET
+	depends on NET && (USB || MMC)
 	help
 	  Support for the GCT GDM72xx WiMAX chip
 
@@ -27,11 +27,11 @@ choice
 
 config WIMAX_GDM72XX_USB
 	bool "USB interface"
-	depends on USB
+	depends on (USB = y || USB = WIMAX_GDM72XX)
 
 config WIMAX_GDM72XX_SDIO
 	bool "SDIO interface"
-	depends on MMC
+	depends on (MMC = y || MMC = WIMAX_GDM72XX)
 
 endchoice