staging: wimax/i2400m: fix byte-order issue

fix sparse byte-order warnings by converting host byte-order
type to __le16 byte-order types before assigning to hdr.length

Signed-off-by: karthik alapati <mail@karthek.com>
Link: https://lore.kernel.org/r/0ae5c5c4c646506d8be871e7be5705542671a1d5.1613921277.git.mail@karthek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>