gpu: nvgpu: update kmdi interfaces

Patch udpates/fixes following issues.
- Updates nvgpu_dbg_gpu_get_mappings_entry.size to u64 to address >4G
limitations.
- Removes offset from original cpuva and unmaps only original mapped
address.
- Call nvgpu_vm_find_mapped_buf_range() in place of
nvgpu_vm_find_mapped_buf() to find the addresses which are not
page aligned.
- Update logic to parse the gpuva while trying to find gpu mappings so
that gpuva which are more than the mapped buffer base address can also
be considered.

Bug 200722275

Change-Id: If33d85db37a9f03a662984c212544a8b2ade471c
Signed-off-by: prsethi <prsethi@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2612129
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Dinesh T <dt@nvidia.com>
Reviewed-by: Vaibhav Kachore <vkachore@nvidia.com>
GVS: Gerrit_Virtual_Submit

include/uapi/linux/nvgpu.h

@@ -546,8 +546,7 @@ struct nvgpu_dbg_gpu_get_mappings_entry {
 	/* out: start of GPU VA for this mapping */
 	__u64 gpu_va;
 	/* out: size in bytes of this mapping */
-	__u32 size;
-	__u32 reserved;
+	__u64 size;
 };
 
 struct nvgpu_dbg_gpu_get_mappings_args {