CVE-2026-53403 fbdev: Fix fb_new_modelist to prevent null-ptr-deref in fb_videomode_to_var

In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix fbnewmodelist to prevent null-ptr-deref in fbvideomodetovar info-var, a framebuffer's current mode, is expected to have a matching entry in info-modelist. vartodisplay relies on this and treats a failed fbmatchmode as...