drm/xe/hwmon: Expose individual VRAM channel temperature

drm/xe/hwmon: Expose individual VRAM channel temperature

Expose individual VRAM temperature attributes.
Update Xe hwmon documentation for this entry.

v2:
 - Avoid using default switch case for VRAM individual temperatures.
 - Append labels with VRAM channel number.
 - Update kernel version in Xe hwmon documentation.

v3:
 - Add missing brackets in Xe hwmon documentation from VRAM channel sysfs.
 - Reorder BMG_VRAM_TEMPERATURE_N macro in xe_pcode_regs.h.
 - Add api to check if VRAM is available on the channel.

v4:
 - Improve VRAM label handling to eliminate temp variable by
   introducing a dedicated array vram_label in xe_hwmon_thermal_info.
 - Remove a magic number.
 - Change the label from vram_X to vram_ch_X.

v5:
 - Address review comments from Raag.
 - Change vram to VRAM in commit title and subject.
 - Refactor BMG_VRAM_TEMPERATURE_N macro.
 - Refactor is_vram_ch_available().
 - Rephrase a comment.
 - Check individual VRAM temperature limits in addition to VRAM
   availability in xe_hwmon_temp_is_visible. (Raag)
 - Move VRAM label change out of this patch.

v6:
 - Use in_range() for VRAM_N index check instead of if check. (Raag)
 - Minor aesthetic changes.

Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Link: https://patch.msgid.link/20260112203521.1014388-5-karthik.poosa@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>