usb: musb: allow building USB_MUSB_TUSB6010 as a module

Commit 1376d92f9 "usb: musb: allow musb and glue layers to be modules"
made the USB_MUSB_TUSB6010 option modular, but actually building
the driver as a module does not work, so various randconfig builds
actually fail. This changes all code that depends on the
option to also check for modular builds, and exports the necessary
symbols.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/arch/arm/mach-omap2/board-n8x0.c b/arch/arm/mach-omap2/board-n8x0.c
index e9d5f4a..2913692 100644
--- a/arch/arm/mach-omap2/board-n8x0.c
+++ b/arch/arm/mach-omap2/board-n8x0.c
@@ -46,7 +46,7 @@
 #define TUSB6010_GPIO_ENABLE	0
 #define TUSB6010_DMACHAN	0x3f
 
-#ifdef CONFIG_USB_MUSB_TUSB6010
+#if defined(CONFIG_USB_MUSB_TUSB6010) || defined(CONFIG_USB_MUSB_TUSB6010_MODULE)
 /*
  * Enable or disable power to TUSB6010. When enabling, turn on 3.3 V and
  * 1.5 V voltage regulators of PM companion chip. Companion chip will then