usb: musb: Fix tusb6010 compile error on blackfin

We have CONFIG_BLACKFIN ifdef redefining all musb registers in
musb_regs.h and tusb6010.h is never included causing a build
error with blackfin-allmodconfig and COMPILE_TEST.

Let's fix the issue by not building tusb6010 if CONFIG_BLACKFIN
is selected.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>