gpu: nvgpu: modify alloc_as ioctl to accept mem size

- Modify NVGPU_GPU_IOCTL_ALLOC_AS and struct nvgpu_alloc_as_args to
accept start address and size of user memory. This allows configurable
address space allocation.
- Modify gk20a_as_alloc_share() and gk20a_vm_alloc_share() to receive
va_range_start and va_range_end values.
- gk20a_vm_alloc_share() initializes vm with low_hole = va_range_start,
and user vma size = (va_range_end - va_range_start).
- Modify nvgpu_as_alloc_space_args and nvgpu_as_free_space_args to
accept 64 bit number of pages.

Bug 2043269
JIRA NVGPU-5302

Change-Id: I243995adf5b7e0e84d6b36abe3b35a5ccabd7a37
Signed-off-by: Vedashree Vidwans <vvidwans@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2385496
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
Tested-by: Sami Kiminki <skiminki@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c

@@ -594,6 +594,9 @@ static int gk20a_ctrl_alloc_as(
 	err = gk20a_as_alloc_share(g, args->big_page_size,
 				   gk20a_as_translate_as_alloc_flags(g,
 					   args->flags),
+				   args->va_range_start,
+				   args->va_range_end,
+				   args->va_range_split,
 				   &as_share);
 	if (err)
 		goto clean_up_file;