drm/i915: Fix DPLCLKA_CFGCR0 bits for Port F.

Since when it got introduced with commit '555e38d2
("drm/i915/cnl: DDI - PLL mapping")' the support for Port F
was wrong, because Port F bits are far from bits used
for A to E.

Since Port F is not used so far we don't need to propagate
Fixes back there.

v2: Reuse _SHIFT definition to avoid complicated duplication (DK).

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180129232223.766-5-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -8759,10 +8759,12 @@ enum skl_power_gate {
  * CNL Clocks
  */
 #define DPCLKA_CFGCR0				_MMIO(0x6C200)
-#define  DPCLKA_CFGCR0_DDI_CLK_OFF(port)	(1 << ((port)+10))
-#define  DPCLKA_CFGCR0_DDI_CLK_SEL_MASK(port)	(3 << ((port)*2))
-#define  DPCLKA_CFGCR0_DDI_CLK_SEL_SHIFT(port)	((port)*2)
-#define  DPCLKA_CFGCR0_DDI_CLK_SEL(pll, port)	((pll) << ((port)*2))
+#define  DPCLKA_CFGCR0_DDI_CLK_OFF(port)	(1 << ((port) ==  PORT_F ? 23 : \
+						      (port)+10))
+#define  DPCLKA_CFGCR0_DDI_CLK_SEL_SHIFT(port)	((port) == PORT_F ? 21 : \
+						(port)*2)
+#define  DPCLKA_CFGCR0_DDI_CLK_SEL_MASK(port)	(3 << DPCLKA_CFGCR0_DDI_CLK_SEL_SHIFT(port))
+#define  DPCLKA_CFGCR0_DDI_CLK_SEL(pll, port)	((pll) << DPCLKA_CFGCR0_DDI_CLK_SEL_SHIFT(port))
 
 /* CNL PLL */
 #define DPLL0_ENABLE		0x46010