drm/i915/guc: avoid FIELD_PREP warning

With gcc-7 and earlier, there are lots of warnings like

In file included from <command-line>:0:0:
In function '__guc_context_policy_add_priority.isra.66',
    inlined from '__guc_context_set_prio.isra.67' at drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:3292:3,
    inlined from 'guc_context_set_prio' at drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:3320:2:
include/linux/compiler_types.h:399:38: error: call to '__compiletime_assert_631' declared with attribute error: FIELD_PREP: mask is not constant
  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
                                      ^
...
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:2422:3: note: in expansion of macro 'FIELD_PREP'
   FIELD_PREP(GUC_KLV_0_KEY, GUC_CONTEXT_POLICIES_KLV_ID_##id) | \
   ^~~~~~~~~~

Make sure that GUC_KLV_0_KEY is an unsigned value to avoid the warning.

Fixes: 77b6f79d ("drm/i915/guc: Update to GuC version 69.0.3")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Julia Filipchuk <julia.filipchuk@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240430164809.482131-1-julia.filipchuk@intel.com

drivers/gpu/drm/i915/gt/uc/abi/guc_klvs_abi.h

@@ -29,9 +29,9 @@
  */
 
 #define GUC_KLV_LEN_MIN				1u
-#define GUC_KLV_0_KEY				(0xffff << 16)
-#define GUC_KLV_0_LEN				(0xffff << 0)
-#define GUC_KLV_n_VALUE				(0xffffffff << 0)
+#define GUC_KLV_0_KEY				(0xffffu << 16)
+#define GUC_KLV_0_LEN				(0xffffu << 0)
+#define GUC_KLV_n_VALUE				(0xffffffffu << 0)
 
 /**
  * DOC: GuC Self Config KLVs