CVE-2025-40015

In the Linux kernel, the following vulnerability has been resolved:

media: stm32-csi: Fix dereference before NULL check

In 'stm32_csi_start', 'csidev->s_subdev' is dereferenced directly while
assigning a value to the 'src_pad'. However the same value is being
checked against NULL at a later point of time indicating that there
are chances that the value can be NULL.

Move the dereference after the NULL check.