usb: musb: Fix randconfig build issues for Kconfig options

Commit 82c02f58 ("usb: musb: Allow multiple glue layers to be
built in") enabled selecting multiple glue layers, which in turn
exposed things more for randconfig builds. If NOP_USB_XCEIV is
built-in and TUSB6010 is a loadable module, we will get:

drivers/built-in.o: In function `tusb_remove':
tusb6010.c:(.text+0x16a817): undefined reference to `usb_phy_generic_unregister'
drivers/built-in.o: In function `tusb_probe':
tusb6010.c:(.text+0x16b24e): undefined reference to `usb_phy_generic_register'
make: *** [vmlinux] Error 1

Let's fix this the same way as commit 70c1ff4b ("usb: musb:
tusb-dma can't be built-in if tusb is not").

And while at it, let's not allow selecting the glue layers except
on platforms really using them unless COMPILE_TEST is specified:

- TUSB6010 is in practise only used on omaps

- DSPS is only used on TI platforms

- UX500 is only used on STE platforms

Cc: Linus Walleij <linus.walleij@linaro.org>
Reported-by: Jim Davis <jim.epost@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>