drm/i915: Fix cs timestamp frequency for ctg/elk/ilk

On ilk the UDW of TIMESTAMP increments every 1000 ns,
LDW is mbz. In order to represent that we'd need 52 bits,
but we only have 32 bits. Even worse most things want to
only deal with 32 bits of timestamp. So let's just set
up the timestamp frequency as if we only had the UDW.

On ctg/elk 63:20 of TIMESTAMP increments every 1/4 ns, 19:0
are mbz. To make life simpler let's ignore the LDW and set up
timestamp frequency based on the UDW only (increments every
1024 ns).

v2: Rebase

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221031135703.14670-2-ville.syrjala@linux.intel.com


Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>