staging: rtl8188eu: change array type to u8

The the last two parameters of write_cam() have type u8.
Change the type of the passed arrays from unsigned char to u8.
Clears a line over 80 characters checkpatch warning.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>