drm/i915/dg1: Enable DPLL for DG1

Add DG1 DPLL Enable register macro and use the macro to enable the
correct DPLL based on PLL id. Although we use
_MG_PLL1_ENABLE/_MG_PLL2_ENABLE these are rather combo phys.

While at it, fix coding style: wrong newlines and use if/else chain

v2: Rewrite original patch from Aditya Swarup based on refactors
upstream

Bspec: 49443, 49206

Cc: Clinton Taylor <Clinton.A.Taylor@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Aditya Swarup <aditya.swarup@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Aditya Swarup <aditya.swarup@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201014191937.1266226-6-lucas.demarchi@intel.com

drivers/gpu/drm/i915/display/intel_dpll_mgr.c

@@ -151,14 +151,14 @@ static i915_reg_t
 intel_combo_pll_enable_reg(struct drm_i915_private *i915,
 			   struct intel_shared_dpll *pll)
 {
-
-	if (IS_JSL_EHL(i915) && (pll->info->id == DPLL_ID_EHL_DPLL4))
+	if (IS_DG1(i915))
+		return DG1_DPLL_ENABLE(pll->info->id);
+	else if (IS_JSL_EHL(i915) && (pll->info->id == DPLL_ID_EHL_DPLL4))
 		return MG_PLL_ENABLE(0);
 
 	return CNL_DPLL_ENABLE(pll->info->id);
-
-
 }
+
 /**
  * intel_prepare_shared_dpll - call a dpll's prepare hook
  * @crtc_state: CRTC, and its state, which has a shared dpll

drivers/gpu/drm/i915/i915_reg.h

@@ -10316,6 +10316,10 @@ enum skl_power_gate {
 #define MG_PLL_ENABLE(tc_port)	_MMIO_PORT((tc_port), _MG_PLL1_ENABLE, \
 					   _MG_PLL2_ENABLE)
 
+/* DG1 PLL */
+#define DG1_DPLL_ENABLE(pll)    _MMIO_PLL3(pll, DPLL0_ENABLE, DPLL1_ENABLE, \
+					   _MG_PLL1_ENABLE, _MG_PLL2_ENABLE)
+
 #define _MG_REFCLKIN_CTL_PORT1				0x16892C
 #define _MG_REFCLKIN_CTL_PORT2				0x16992C
 #define _MG_REFCLKIN_CTL_PORT3				0x16A92C