drm/i915: fix shift warning

Randconfig builds on 32-bit machines show lots of warnings for
the i915 driver for passing a 32-bit value into __const_hweight64():

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c:2584:9: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        return hweight64(VDBOX_MASK(&i915->gt));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/const_hweight.h:29:49: note: expanded from macro 'hweight64'
 #define hweight64(w) (__builtin_constant_p(w) ? __const_hweight64(w) : __arch_hweight64(w))

Change it to hweight_long() to avoid the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20210103135158.3591442-1-arnd@kernel.org

drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c

@@ -2582,7 +2582,7 @@ static int eb_submit(struct i915_execbuffer *eb, struct i915_vma *batch)
 
 static int num_vcs_engines(const struct drm_i915_private *i915)
 {
-	return hweight64(VDBOX_MASK(&i915->gt));
+	return hweight_long(VDBOX_MASK(&i915->gt));
 }
 
 /*