gpio: mxs: GPIO_MXS should not default to y unconditionally

gpio: mxs: GPIO_MXS should not default to y unconditionally

commit 97c6e28d388a5000d780d2a63c32f422827f5aa3 upstream.

Merely enabling CONFIG_COMPILE_TEST should not enable additional code.
To fix this, restrict the automatic enabling of GPIO_MXS to ARCH_MXS,
and ask the user in case of compile-testing.

Fixes: 6876ca311bfca5d7 ("gpio: mxs: add COMPILE_TEST support for GPIO_MXS")
Cc: <stable@vger.kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>