usb: musb: add generic usb phy dependencies

Multiple musb glue drivers depend on the generic usb phy support,
but fail to list it as a dependency in Kconfig. This results
in build erros like:

drivers/built-in.o: In function `am35x_remove':
:(.text+0xadacc): undefined reference to `usb_phy_generic_unregister'
drivers/built-in.o: In function `am35x_probe':
:(.text+0xae1c8): undefined reference to `usb_phy_generic_register'
:(.text+0xae244): undefined reference to `usb_phy_generic_unregister'
drivers/built-in.o: In function `jz4740_remove':
:(.text+0xaf648): undefined reference to `usb_phy_generic_unregister'
drivers/built-in.o: In function `jz4740_musb_init':
:(.text+0xaf694): undefined reference to `usb_phy_generic_register'

This adds the ones that are missing.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>