drm/i915/gt: Use sysfs_emit() and sysfs_emit_at()

Use sysfs_emit() and sysfs_emit_at() in show() callback
as recommended by Documentation/filesystems/sysfs.rst

Cc: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230130131358.16800-1-nirmoy.das@intel.com