vfs: mark variables as uninitialized to make gcc happy

Both kernel_type and kernel_div will pick up values throughout the function, either as NULL or some other value. To make GCC happy, mark it as uninitialized.

Change-Id: Ibfa249db67d3969fa319b4bcf131026d27024e38
Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>