atomisp: avoid warning about unused function

The atomisp_mrfld_power() function isn't actually ever called, because
the two call-sites have commented out the use because it breaks on some
platforms.  That results in:

  drivers/staging/media/atomisp/pci/atomisp_v4l2.c:764:12: warning: ‘atomisp_mrfld_power’ defined but not used [-Wunused-function]
    764 | static int atomisp_mrfld_power(struct atomisp_device *isp, bool enable)
        |            ^~~~~~~~~~~~~~~~~~~

during the build.

Rather than commenting out the use entirely, just disable it
semantically instead (using a "0 &&" construct), leaving the call in
place from a syntax standpoint, and avoiding the warning.

I really don't want my builds to have any warnings that can then hide
real issues.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/staging/media/atomisp/pci/atomisp_v4l2.c

@@ -824,17 +824,15 @@ static int atomisp_mrfld_power(struct atomisp_device *isp, bool enable)
 /* Workaround for pmu_nc_set_power_state not ready in MRFLD */
 int atomisp_mrfld_power_down(struct atomisp_device *isp)
 {
-	return 0;
-// FIXME: at least with ISP2401, the code below causes the driver to break
-//	return atomisp_mrfld_power(isp, false);
+// FIXME: at least with ISP2401, enabling this code causes the driver to break
+	return 0 && atomisp_mrfld_power(isp, false);
 }
 
 /* Workaround for pmu_nc_set_power_state not ready in MRFLD */
 int atomisp_mrfld_power_up(struct atomisp_device *isp)
 {
-	return 0;
-// FIXME: at least with ISP2401, the code below causes the driver to break
-//	return atomisp_mrfld_power(isp, true);
+// FIXME: at least with ISP2401, enabling this code causes the driver to break
+	return 0 && atomisp_mrfld_power(isp, true);
 }
 
 int atomisp_runtime_suspend(struct device *dev)