staging: ks7010: refactor hostif_sme_power_mgmt_set function

Some minor changes have been done in this function to clean
it a bit:
    - POWER_MGMT_ACTIVE and default case are the same so
      just handle that with the same block of code,
    - POWER_MGMT_SAVE1 replaces if-else with a ternary operator.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>