kernel: update fb-sys-fops package for kernel 6.12

kernel: update fb-sys-fops package for kernel 6.12

For kernel 6.12 the fb-sys-fops module setting has been renamed
from CONFIG_FB_SYS_FOPS to CONFIG_FB_SYSMEM_FOPS.
This patch sets the KCONFIG value depending on the kernel version.

Ref: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-6.12.y&id=27ad64eac10fcb25fcbfb813921f4d30b3458e13

Signed-off-by: Mieczyslaw Nalewaj <namiltd@yahoo.com>
Link: https://github.com/openwrt/openwrt/pull/16547
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>