uboot-imx

relocate-rela: use compiler.h endian macros

Use the endian macros from u-boot's compiler.h instead of duplicating
the definitions.

This also avoids a build error on OpenBSD by removing swap64 which
collides with a system definition in endian.h pulled in by inttypes.h.

Signed-off-by: Jonathan Gray <jsg@jsg.id.au>