spi: pxa2xx: Enable support for compile-testing

spi: pxa2xx: Enable support for compile-testing

m68k/allmodconfig:

    WARNING: unmet direct dependencies detected for SPI_PXA2XX
      Depends on [n]: SPI [=y] && SPI_MASTER [=y] && (ARCH_PXA || ARCH_MMP || PCI [=n] || ACPI)
      Selected by [m]:
      - SND_SOC_INTEL_BDW_RT5677_MACH [=m] && SOUND [=m] && !UML && SND [=m] && SND_SOC [=m] && SND_SOC_INTEL_MACH [=y] && (SND_SOC_INTEL_HASWELL [=n] || SND_SOC_SOF_BROADWELL [=m]) && I2C [=m] && (I2C_DESIGNWARE_PLATFORM [=m] || COMPILE_TEST [=y]) && (GPIOLIB [=y] || COMPILE_TEST [=y]) && (X86_INTEL_LPSS || COMPILE_TEST [=y]) && SPI_MASTER [=y]

This happens because SND_SOC_INTEL_BDW_RT5677_MACH selects SPI_PXA2XX,
and the former depends on COMPILE_TEST, while the latter does not.

Fix this by enabling compile-testing for SPI_PXA2XX.

Fixes: 630db1549356f644 ("ASoC: Intel: bdw-rt5677: fix Kconfig dependencies")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200210093027.6672-1-geert@linux-m68k.org
Signed-off-by: Mark Brown <broonie@kernel.org>