sata_dwc_460ex: disable COMPILE_TEST again

Commit 84683a7e ("sata_dwc_460ex: enable COMPILE_TEST for the
driver") enabled this driver for non-ppc460-ex platforms, but it was
then disabled for ARM and ARM64 by commit 2de5a9c0 ("sata_dwc_460ex:
disable compilation on ARM and ARM64") because it's too noisy and
broken.

This disabled is entirely, because it's too noisy on x86-64 too, and
there's no point in disabling architectures one by one.  At a minimum,
the code isn't 64-bit clean, and even on 32-bit it is questionable
whether it makes sense.

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>