drm/gem: Fix inconsistent plane dimension calculation in drm_gem_fb_init_with_funcs()

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CVE-2026-46209 · Microsoft / collected KEV context

cve-program · CVE-2026-46209

• https://git.kernel.org/stable/c/11427ad6c9f0def5ce567982b785da3191946430
• https://git.kernel.org/stable/c/adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad
• https://git.kernel.org/stable/c/22922f7dae74409fc4bf0f1142710cb6b8ce8cc2
• https://git.kernel.org/stable/c/6b992591e04f2cce813bcf239b354f375bbf84d3
• https://git.kernel.org/stable/c/1da4ab7189f1064b3b712b388772c008b4d82580
• https://git.kernel.org/stable/c/1a17ea9861e89585361caa8bc231bd22dc6dbe7d
• https://git.kernel.org/stable/c/c5fc49d8470c5ebf3b41607600f277158f159950
• https://git.kernel.org/stable/c/3d4c2268bd7243c3780fe32bf24ff876da272acf

No related operational record is retained in the current change model.