LinuxKPI: Use macro for implementation of some dma_map_* functions

This allows to remove unimplemented attrs parameter which type differs
between Linux kernel versions and to compile both drm-kmod and ofed
callers unmodified.
Also convert it to 'unsigned long' type to match modern Linuxes.

Reviewed by: hselasky
Differential revision: https://reviews.freebsd.org/D30932

(cherry picked from commit 98a6984a9e10c5c1677643eb4d9a758e3af131da)