drm/v3d: Fix perfmon build error/warning

Move static const array into the source file to fix the "defined but not
used" errors.

The fix is perhaps not the prettiest due hand crafting the array sizes
in v3d_performance_counters.h, but I did add some build time asserts to
validate the counts look sensible, so hopefully it is good enough for a
quick fix.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Fixes: 3cbcbe01 ("drm/v3d: Add Performance Counters descriptions for V3D 4.2 and 7.1")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202405211137.hueFkLKG-lkp@intel.com/Cc

: Maíra Canal <mcanal@igalia.com>
Cc: Iago Toral Quiroga <itoral@igalia.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240604160210.24073-1-tursulin@igalia.com