staging: wilc1000: use kernel define byte order macros

This patch removes define BIG_ENDIAN and use kernel define byte order macros
instead of swap itself. Remove unused BYTE_SWAP macro and __CHECK_ENDIAN__
in Makefile also.

Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>