drm/xe/regs: remove a duplicate definition for RING_CTL_SIZE(size)

drm/xe/regs: remove a duplicate definition for RING_CTL_SIZE(size)

Commit b79e8fd954c4 ("drm/xe: Remove dependency on intel_engine_regs.h")
introduced an internal set of engine registers, however, as part of this
change, it has also introduced two duplicate `define' lines for
`RING_CTL_SIZE(size)'. This commit was introduced to the tree in v6.8-rc1.

While this is harmless as the definitions did not change, so no compiler
warning was observed.

Drop this line anyway for the sake of correctness.

Cc: stable@vger.kernel.org # v6.8-rc1+
Fixes: b79e8fd954c4 ("drm/xe: Remove dependency on intel_engine_regs.h")
Signed-off-by: Mingcong Bai <jeffbai@aosc.io>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250225073104.865230-1-jeffbai@aosc.io
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>