ALSA: hdspm - cleanup __user tags in ioctl()

This makes the code cleaner and silences a Sparse complaint:
sound/pci/rme9652/hdspm.c:6341:23: warning: incorrect type in assignment (incompatible argument 4 (different address spaces))
sound/pci/rme9652/hdspm.c:6341:23:    expected int ( *ioctl )( ... )
sound/pci/rme9652/hdspm.c:6341:23:    got int ( static [toplevel] *<noident> )( ... )
sound/pci/rme9652/hdspm.c:6102:44: warning: dereference of noderef expression
sound/pci/rme9652/hdspm.c:6225:50: warning: dereference of noderef expression
sound/pci/rme9652/hdspm.c:6264:50: warning: dereference of noderef expression
sound/pci/rme9652/hdspm.c:6283:50: warning: dereference of noderef expression
sound/pci/rme9652/hdspm.c:6289:59: warning: dereference of noderef expression

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>