dsp_ioctl: fix type of variable used to store ioctl request
dsp_ioctl: fix type of variable used to store ioctl request

PR:		kern/156433
Submitted by:	Grigori Goronzy <greg@chown.ath.cx>
Reviewed by:	hselasky
Approved by:	re (kib)
MFC after:	1 week

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase