staging: ks7010: add explicit check to 'size' variables

When checking the value of a variable that holds a 0 an explicit check
is good style. i.e

  -    if (!size)
  +    if (size == 0)

Update checks on 'numerical' variables to use explicit checks.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>