drm/msm/a6xx: Replace kcalloc() with kvzalloc()

In order to reduce chance of allocation failure while capturing a6xx
gpu state, use kvzalloc() instead of kcalloc() in state_kcalloc().

Indirectly, this patch helps to fix leaking memory allocated for
gmu_debug object.

Fixes: b859f9b0

 (drm/msm/gpu: Snapshot GMU debug buffer)
Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/505074/
Link: https://lore.kernel.org/r/20220928124830.1.I8ea24a8d586b4978823b848adde000f92f74d5c2@changeid
Signed-off-by: Rob Clark <robdclark@chromium.org>