Add support for AMD GTT Memory

[DocMAX]

Can you please add a bar to nvtop to show GTT Memory usage (beside VRAM) on AMD GPUs?

[Crandel]

Upvote this request. I'm using AMD integrated iGpu with only 512 MiB VRAM and 50 GiB GTT ram. Need to use amdgpu_top for it. Wait for it a lot.

[TinyServal]

This info is pretty trivial to query from libdrm, but adding a new memory progress bar on the same line makes them way too narrow. I'm not much of a UI person and some ideas I prototyped didn't look very good. Any ideas on how the UI can be refactored to accommodate another memory bar? @Syllo

[TinyServal]

It would be nice if we can move the memory progress bars to a new line below, as the encoder/decoder display logic is already quite messy.

Existing layout:

 Device 0 [AMD Radeon Graphics] Integrated GPU RX: N/A TX: N/A
 GPU 1900MHz MEM 1000MHz TEMP  36°C   CPU-FAN   POW   4 W
 GPU[                               0%] MEM[                  0.014Gi/8.000Gi]

 Device 0 [AMD Radeon Graphics] Integrated GPU RX: N/A TX: N/A
 GPU 1900MHz MEM 1000MHz TEMP  36°C   CPU-FAN   POW   4 W
 GPU[                 0%] MEM[    0.014Gi/8.000Gi] ENC[      0%] DEC[      0%]

Proposed layout for GTT devices:

 Device 0 [AMD Radeon Graphics] Integrated GPU RX: N/A TX: N/A
 GPU 1900MHz MEM 1000MHz TEMP  36°C   CPU-FAN   POW   4 W
 GPU[                                                                      0%]
 MEM[                  0.014Gi/8.000Gi] GTT[                  0.014Gi/8.000Gi]

 Device 0 [AMD Radeon Graphics] Integrated GPU RX: N/A TX: N/A
 GPU 1900MHz MEM 1000MHz TEMP  36°C   CPU-FAN   POW   4 W
 GPU[                                          0%] ENC[      0%] DEC[      0%]
 MEM[                  0.014Gi/8.000Gi] GTT[                  0.014Gi/8.000Gi]

Proposed layout for devices that doesn't use GTT:

 Device 0 [NVIDIA RTX A4000] PCIe GEN 1@ 1x RX: 585.0 KiB/s TX: 537.0 KiB/s
 GPU 210MHz  MEM 405MHz  TEMP  56°C  FAN  41%   POW  19 / 140 W
 GPU[                                                                   0%]
 MEM[|||||||||||||                                       12.571Gi/15.992Gi]

 Device 0 [NVIDIA RTX A4000] PCIe GEN 1@ 1x RX: 634.0 KiB/s TX: 537.0 KiB/s
 GPU 210MHz  MEM 405MHz  TEMP  56°C  FAN  41%   POW  19 / 140 W
 GPU[                                       0%] ENC[      0%] DEC[      0%]
 MEM[|||||||||||||                                       12.571Gi/15.992Gi]