drm/nouveau/clk: Move a variable assignment behind a null pointer check in nvkm_pstate_new()

The address of a data structure member was determined before
a corresponding null pointer check in the implementation of
the function “nvkm_pstate_new”.

Thus avoid the risk for undefined behaviour by moving the assignment
for the variable “cstate” behind the null pointer check.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6435d829-2c9b-a3f7-c8cd-cf923508a092@web.de

drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c

@@ -417,7 +417,6 @@ nvkm_pstate_new(struct nvkm_clk *clk, int idx)
 		return 0;
 
 	pstate = kzalloc(sizeof(*pstate), GFP_KERNEL);
-	cstate = &pstate->base;
 	if (!pstate)
 		return -ENOMEM;
 
@@ -427,6 +426,7 @@ nvkm_pstate_new(struct nvkm_clk *clk, int idx)
 	pstate->fanspeed = perfE.fanspeed;
 	pstate->pcie_speed = perfE.pcie_speed;
 	pstate->pcie_width = perfE.pcie_width;
+	cstate = &pstate->base;
 	cstate->voltage = perfE.voltage;
 	cstate->domain[nv_clk_src_core] = perfE.core;
 	cstate->domain[nv_clk_src_shader] = perfE.shader;