drm/i915/skl: Structure/enum definitions for SKL clocks

Adding structure/enum for SKL clocking implementation.

v2: Addressed Damien's comment
	- Removed internal structure from this header file

v3: Stove this into the generic intel_dpll_id enum and give them the established
DPLL_ID_ prefixes. (Daniel)

v4: - We'll only try to share DPLL1/2/3, leaving DPLL0 to eDP
    - Use SKL in the skylake shared DPLL names
    - Re-add the skl_dpll enum
    (Damien)

v5: Remove SKL_DPLL_NONE (Daniel)

v6: Modified as per review comments from Paulo
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Satheeshakrishna M <satheeshakrishna.m@intel.com> (v2)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> (v4,v5)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v3)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -213,10 +213,15 @@ enum intel_dpll_id {
 	/* real shared dpll ids must be >= 0 */
 	DPLL_ID_PCH_PLL_A = 0,
 	DPLL_ID_PCH_PLL_B = 1,
+	/* hsw/bdw */
 	DPLL_ID_WRPLL1 = 0,
 	DPLL_ID_WRPLL2 = 1,
+	/* skl */
+	DPLL_ID_SKL_DPLL1 = 0,
+	DPLL_ID_SKL_DPLL2 = 1,
+	DPLL_ID_SKL_DPLL3 = 2,
 };
-#define I915_NUM_PLLS 2
+#define I915_NUM_PLLS 3
 
 struct intel_dpll_hw_state {
 	/* i9xx, pch plls */
@@ -256,6 +261,11 @@ struct intel_shared_dpll {
 			     struct intel_dpll_hw_state *hw_state);
 };
 
+#define SKL_DPLL0 0
+#define SKL_DPLL1 1
+#define SKL_DPLL2 2
+#define SKL_DPLL3 3
+
 /* Used by dp and fdi links */
 struct intel_link_m_n {
 	uint32_t	tu;