drm/i915/psr: Update PSR2 resolution check for Cannonlake

drm/i915/psr: Update PSR2 resolution check for Cannonlake

In fact, apply the Cannonlake resolution check for all >= Gen-10 platforms
to be safe.

v3: Update GLK too. (Ville)
    Longer variable names.
    if-else in place of ternary operator.
v2: Use local variables for resolution limits and print them (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Elio Martinez Monroy <elio.martinez.monroy@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180306203355.29292-1-dhinakaran.pandiyan@intel.com