gpu: nvgpu: fix sim STR30 CERT C violations

Make path a pointer to const char to avoid attempt to
modify string literal.

Error: CERT STR30-C:
drivers/gpu/nvgpu/common/sim/sim_netlist.c:363:
cert_violation: Assigning or casting string literal
 ""GRCTX_GEN_CTX_REGS_BASE_INDEX"" to a pointer to non-const.

Jira NVGPU-3560

Change-Id: I22dacbbd210a43c41aef2532c5ddb1429d5c9153
Signed-off-by: Nitin Kumbhar <nkumbhar@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2122101
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svc-mobile-misra <svc-mobile-misra@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/sim/sim.c

@@ -219,7 +219,7 @@ static int issue_rpc_and_wait(struct gk20a *g)
 }
 
 static void nvgpu_sim_esc_readl(struct gk20a *g,
-		char *path, u32 index, u32 *data)
+		const char *path, u32 index, u32 *data)
 {
 	int err;
 	size_t pathlen = strlen(path);

drivers/gpu/nvgpu/common/sim/sim_pci.c

@@ -185,7 +185,7 @@ static int issue_rpc_and_wait(struct gk20a *g)
 }
 
 static void nvgpu_sim_esc_readl(struct gk20a *g,
-		char *path, u32 index, u32 *data)
+		const char *path, u32 index, u32 *data)
 {
 	int err;
 	size_t pathlen = strlen(path);

drivers/gpu/nvgpu/include/nvgpu/sim.h

@@ -37,7 +37,7 @@ struct sim_nvgpu {
 	void (*sim_init_late)(struct gk20a *g);
 	void (*remove_support)(struct gk20a *g);
 	void (*esc_readl)(
-		struct gk20a *g, char *path, u32 index, u32 *data);
+		struct gk20a *g, const char *path, u32 index, u32 *data);
 };
 #ifdef __KERNEL__
 #include "linux/sim.h"