drm/xe/step: define more steppings E-J

These are primarily needed for compat reasons with display code in
upcoming changes. There's no harm in having them.

While at it, add a comment about the requirement to match against GMD ID
value spacing.
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/88074394509d4849f8ec6ab5776394b961032cd0.1724180287.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/xe/xe_step_types.h

@@ -17,6 +17,10 @@ struct xe_step_info {
 
 #define STEP_ENUM_VAL(name)  STEP_##name,
 
+/*
+ * Always define four minor steppings 0-3 for each stepping to match GMD ID
+ * spacing of values. See xe_step_gmdid_get().
+ */
 #define STEP_NAME_LIST(func)		\
 	func(A0)			\
 	func(A1)			\
@@ -34,7 +38,30 @@ struct xe_step_info {
 	func(D1)			\
 	func(D2)			\
 	func(D3)			\
-	func(E0)
+	func(E0)			\
+	func(E1)			\
+	func(E2)			\
+	func(E3)			\
+	func(F0)			\
+	func(F1)			\
+	func(F2)			\
+	func(F3)			\
+	func(G0)			\
+	func(G1)			\
+	func(G2)			\
+	func(G3)			\
+	func(H0)			\
+	func(H1)			\
+	func(H2)			\
+	func(H3)			\
+	func(I0)			\
+	func(I1)			\
+	func(I2)			\
+	func(I3)			\
+	func(J0)			\
+	func(J1)			\
+	func(J2)			\
+	func(J3)
 
 /*
  * Symbolic steppings that do not match the hardware. These are valid both as gt