staging: r8188eu: Fix sparse endianness warnings.

This patch fixes sparse warnings about the endianness of different
integers in the driver.

Fixes: 15865124 ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Charlie Sands <sandsch@northvilleschools.net>
Link: https://lore.kernel.org/r/YkPK/QmLAp3BkygY@sckzor-linux.localdomain


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