drm/xe: Sample gpu timestamp closer to exec queues

Move the force_wake_get to the beginning of the function so the gpu
timestamp can be closer to the sampled value for exec queues. This
avoids additional delays waiting for force wake ack which can make the
proportion between cycles/total_cycles fluctuate around the real value.
For a gputop-like application getting 2 samples to calculate the
utilization:

	sample 0:
		read_exec_queue_timestamp
					<<<< (A)
		read_gpu_timestamp
	sample 1:
		read_exec_queue_timestamp
					<<<<< (B)
		read_gpu_timestamp

In the above case, utilization can be bigger or smaller than it should
be, depending on if (A) or (B) receives additional delay, respectively.

With this a LNL system that was failing on
`xe_drm_fdinfo --r utilization-single-full-load` after ~60 iterations,
get to run to 100 without a failure. This is still not perfect, and it's
easy to introduce errors by just loading the CPU with `stress --cpu
$(nproc)` - the same igt test in this case fails after 2 or 3
iterations. That will be dealt with in the test itself, using a longer
sampling period.

v2: Rename function and add another to get "any engine", preparing for
    caching the hwe in future (Umesh / Jonathan)

Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241108053318.3483678-3-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>