drm/i915: Correct duplicated/misplaced GT register definitions

XEHPSDV_FLAT_CCS_BASE_ADDR, GEN8_L3_LRA_1_GPGPU, and MMCD_MISC_CTRL were
duplicated between i915_reg.h and intel_gt_regs.h.  These are all GT
registers, so we should drop the copy from i915_reg.h.

XEHPSDV_TILE0_ADDR_RANGE was defined in i915_reg.h, but really belongs
in intel_gt_regs.h.  Move it.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220624210328.308630-1-matthew.d.roper@intel.com