staging/ks7010: Fix type assignment for struct hostif_hdr

Sparse spits out a warnings about __le16 and unsigned short assignment.
Change the type of size and event members of struct hostif_hdr
to __le16 and correct conversion to the proper cpu type.

Signed-off-by: Cezary Gapinski <gapalinux@gmail.com>
Reviewed-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>