Platform: Remove warning in Musca-S1 ioctl function

Remove an assignment which is not needed in a Musca-S1 ioctl
function to get rid of a compiler warning.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I737d08a97f194addd735ebccae46a550aa2c83eb
1 file changed