drm/i915/gt: Remove unncessary {} from if-else

Fix checkpatch.pl error:

WARNING: braces {} are not necessary for any arm of this statement

Signed-off-by: Gilbert Adikankwu <gilbertadikankwu@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231026105623.480172-1-gilbertadikankwu@gmail.com