drm/msm/dpu: fix error pointer dereference in msm_kms_init_aspace()

If msm_gem_address_space_create() fails, then return right away.
Otherwise it leads to a Oops when we dereference "aspace" on the next
line.

Fixes: eabba31a ("drm/msm: register a fault handler for display mmu faults")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/639357/
Link: https://lore.kernel.org/r/3221e88c-3351-42e6-aeb1-69f4f014b509@stanley.mountain


[DB: fixed commit id]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>