atomisp: remove a now unused var

A previous cleanup patch removed the usage of the ret var.

So, drop it.

Link: https://lore.kernel.org/linux-media/a03a4a3e9aad2b8154018c323cf7766266990724.1616430113.git.mchehab+huawei@kernel.org


Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>