Add definitions for various pipe timestamp registers:
- frame timestamp (last start of vblank) (g4x+), already had this defined
- flip timestamp (when SURF was last written) (g4x+)
- flipdone timestamp (when last flipdone was signalled) (tgl+)

Note that on pre-tgl the flip related timestamps are only updated
for primary plane flips, but on tgl+ we can select which plane
updates them (via PIPE_MISC2). Let's define those related bits
as well.

Curiously VLV/CHV do not have the frame/flip timestamp registers,
despite all the other related registers being inherited from g4x.
This means we can get rid of the pipe_offsets[] usage for these,
and thus the implicit dev_priv is gone as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230314130255.23273-4-ville.syrjala@linux.intel.comReviewed-by: Jouni Högander <jouni.hogander@intel.com>