ums: move all variable declarations to the start of the block

It's easier to assign values to the variables inside an if statement body
if the assignment and declaration are separate.

Cc: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>