drm/i915/bxt: Fix off-by-one error in Broxton PLL IDs

After the commit below the Broxton PLL IDs had an off-by-one error, so
fix this up. Also add a missing brace at intel_shared_dpll_init(), it
happened to compile only due to the way the IS_BROXTON macro is defined.

v2:
- remove debugging left-over

Fixes: a3c988ea ("drm/i915: Make SKL/KBL DPLL0 managed by the shared dpll code")
CC: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
CC: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457978134-12362-1-git-send-email-imre.deak@intel.com