gpu: nvgpu: gk20a: Allow regops lists longer than 128

Process long regops lists in 4-kB fragments, overcoming the overly
low limit of 128 reg ops per IOCTL call. Bump the list limit to 1024
and report the limit in GPU characteristics.

Bug 200248726

Change-Id: I3ad49139409f32aea8b1226d6562e88edccc8053
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: http://git-master/r/1253716
(cherry picked from commit 22314619b28f52610cb8769cd4c3f9eb01904eab)
Reviewed-on: http://git-master/r/1266652
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

include/uapi/linux/nvgpu.h

@@ -220,6 +220,11 @@ struct nvgpu_gpu_characteristics {
 	__u8  vbios_oem_version;
 	__u32 vbios_version;
 
+	/* NVGPU_DBG_GPU_IOCTL_REG_OPS: the upper limit for the number
+	 * of regops */
+	__u32 reg_ops_limit;
+	__u32 reserved1;
+
 	/* Notes:
 	   - This struct can be safely appended with new fields. However, always
 	     keep the structure size multiple of 8 and make sure that the binary