drm/amdgpu/mes11: optimize MES pipe FW version fetching

Don't fetch it again if we already have it.  It seems the
registers don't reliably have the value at resume in some
cases.

Fixes: 028c3fb3 ("drm/amdgpu/mes11: initiate mes v11 support")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4083


Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org