staging: wilc1000: remove preprocessor conditionals unused

This patch removes unused preprocessor conditionals for the
PLAT_AML8726_M3_BACKUP and PLAT_AML8726_M3 which are not used and so
dead codes. They are also platform-dependent codes.

Signed-off-by: Tony Cho <tony.cho@atmel.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>