drm/i915: Fix cmdparser STORE/LOAD command descriptors

Fixes regression from
commit f1afe24f0e736b9d7f2275e2b1504af3fe612f2a
Author: Arun Siluvery <arun.siluvery@linux.intel.com>
Date:   Tue Aug 4 16:22:20 2015 +0100

    drm/i915: Change SRM, LRM instructions to use correct length

which forgot to account for the length bias when declaring the fixed
length.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91844
Reported-by: Andreas Reis <andreas.reis@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_cmd_parser.c

@@ -124,14 +124,14 @@ static const struct drm_i915_cmd_descriptor common_cmds[] = {
 	CMD(  MI_STORE_DWORD_INDEX,             SMI,   !F,  0xFF,   R  ),
 	CMD(  MI_LOAD_REGISTER_IMM(1),          SMI,   !F,  0xFF,   W,
 	      .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 2 }    ),
-	CMD(  MI_STORE_REGISTER_MEM,            SMI,    F,  1,     W | B,
+	CMD(  MI_STORE_REGISTER_MEM,            SMI,    F,  3,     W | B,
 	      .reg = { .offset = 1, .mask = 0x007FFFFC },
 	      .bits = {{
 			.offset = 0,
 			.mask = MI_GLOBAL_GTT,
 			.expected = 0,
 	      }},						       ),
-	CMD(  MI_LOAD_REGISTER_MEM,             SMI,    F,  1,     W | B,
+	CMD(  MI_LOAD_REGISTER_MEM,             SMI,    F,  3,     W | B,
 	      .reg = { .offset = 1, .mask = 0x007FFFFC },
 	      .bits = {{
 			.offset = 0,