drm/hisilicon: Add depends on MMU

The Kconfig symbol depended on MMU but was dropped by the commit
acad3fe ("drm/hisilicon: Removed the dependency on the mmu")
because it already had as a dependency ARM64 that already selects MMU.

But later, commit a0f25a6 ("drm/hisilicon/hibmc: Allow to be built
if COMPILE_TEST is enabled") allowed the driver to be built for non-ARM64
when COMPILE_TEST is set but that could lead to unmet direct dependencies
and linking errors.

Prevent a kconfig warning when MMU is not enabled by making
DRM_HISI_HIBMC depend on MMU.

WARNING: unmet direct dependencies detected for DRM_TTM
  Depends on [n]: HAS_IOMEM [=y] && DRM [=m] && MMU [=n]
  Selected by [m]:
  - DRM_TTM_HELPER [=m] && HAS_IOMEM [=y] && DRM [=m]
  - DRM_HISI_HIBMC [=m] && HAS_IOMEM [=y] && DRM [=m] && PCI [=y] && (ARM64 || COMPILE_TEST [=y])

Fixes: acad3fe ("drm/hisilicon: Removed the dependency on the mmu")
Signed-off-by: Randy Dunlap <[email protected]>
Cc: Gerd Hoffmann <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Cc: Xinliang Liu <[email protected]>
Cc: Tian Tao  <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Xinwei Kong <[email protected]>
Cc: Chen Feng <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Reviewed-by: Javier Martinez Canillas <[email protected]>
Signed-off-by: Javier Martinez Canillas <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

drivers/gpu/drm/hisilicon/hibmc/Kconfig

@@ -2,6 +2,7 @@
 config DRM_HISI_HIBMC
 	tristate "DRM Support for Hisilicon Hibmc"
 	depends on DRM && PCI && (ARM64 || COMPILE_TEST)
+	depends on MMU
 	select DRM_KMS_HELPER
 	select DRM_VRAM_HELPER
 	select DRM_TTM