drm/msm/a6xx: add CONFIG_QCOM_LLCC dependency

drm/msm/a6xx: add CONFIG_QCOM_LLCC dependency

When LLCC support is in a loadable module, the adreno support
cannot be built-in:

aarch64-linux-ld: drivers/gpu/drm/msm/adreno/a6xx_gpu.o: in function `a6xx_gpu_init':
a6xx_gpu.c:(.text+0xe0): undefined reference to `llcc_slice_getd'
a6xx_gpu.c:(.text+0xe0): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `llcc_slice_getd'
aarch64-linux-ld: a6xx_gpu.c:(.text+0xec): undefined reference to `llcc_slice_getd'
a6xx_gpu.c:(.text+0xec): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `llcc_slice_getd'
aarch64-linux-ld: drivers/gpu/drm/msm/adreno/a6xx_gpu.o: in function `a6xx_destroy':
a6xx_gpu.c:(.text+0x274): undefined reference to `llcc_slice_putd'
a6xx_gpu.c:(.text+0x274): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `llcc_slice_putd'
aarch64-linux-ld: a6xx_gpu.c:(.text+0x27c): undefined reference to `llcc_slice_putd'

Add a Kconfig dependency that disallows the broken configuration
but allows all working ones.

Fixes: a955417782c3 ("drm/msm/a6xx: Add support for using system cache(LLC)")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210103140407.3917405-1-arnd@kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602215252.695994-3-keescook@chromium.org