It seems the driver ships a private include file which attempts to redefine some of the common byte swap functions of the kernel, leading to the issue you've seen.
I only quickly build tested my Makefile on x86, maybe it is different in this regard. As a quick hack, try passing USER_EXTRA_CFLAGS="-D_LINUX_BYTEORDER_SWAB_H" to make which should inhibit the redefinitions.
Updated Makefile: