staging: ozwpan: Reduced size of oz_evtlist structure.

This structure is used in an ioctl definition and was causing the
64-bit PowerPC build to fail. The size of the array in the structure
has been reduced to fix this.

Signed-off-by: Chris Kelly <ckelly@ozmodevices.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>