drm/i915/gt: Remove bogus comment on IVB_FBC_RT_BASE_UPPER

The comment on the parameter being 0 to avoid the read back doesn't
apply as this is not a call to wa_add(), but rather to
wa_write_clr_set(). So, this register is actually checked and it's
according to the Bspec that the register is RW, not RO.
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230630203509.1635216-7-lucas.demarchi@intel.com

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -666,7 +666,7 @@ static void icl_ctx_workarounds_init(struct intel_engine_cs *engine,
 	/* Wa_1604278689:icl,ehl */
 	wa_write(wal, IVB_FBC_RT_BASE, 0xFFFFFFFF & ~ILK_FBC_RT_VALID);
 	wa_write_clr_set(wal, IVB_FBC_RT_BASE_UPPER,
-			 0, /* write-only register; skip validation */
+			 0,
 			 0xFFFFFFFF);
 
 	/* Wa_1406306137:icl,ehl */