media: dib8000: avoid division by 0 in dib8000_set_dds()

media: dib8000: avoid division by 0 in dib8000_set_dds()

In dib8000_set_dds(), 1 << 26 (67108864) divided by e.g. 1 apparently can't
fit into 16-bit variable unit_khz_dds_val, being truncated to 0; this will
cause division by 0 while calling dprintk() with debugging enabled (via the
module parameter).  Use s32 instead of s16 to declare the variable, getting
rid of the cast to u16 in the *else* branch as well...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: 173a64cb3fcf ("[media] dib8000: enhancement")
Cc: stable@vger.kernel.org
Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>