stand/common/load_elf: Do kernel module relocations for PPC

reloc_ptr() skips relocations for the kernel module, because on most
platforms the kernel is ET_EXEC and this is not required.  On PPC,
the kernel is ET_DYN and we need to relocate here, otherwise the
module metadata will not be loaded properly and the kernel module
will have an incorrect version, preventing module dependencies from
resolving.

This fixes loading kernel modules from loader.conf on powerpc.

Diagnosed by:	jrtc27
Reviewed by:	jrtc27, adrian
Sponsored by:	https://www.patreon.com/bsdivy
Differential Revision:	https://reviews.freebsd.org/D56457

stand/common/load_elf.c

@@ -1282,10 +1282,11 @@ __elfN(reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
 	int error;
 
 	/*
-	 * The kernel is already relocated, but we still want to apply
-	 * offset adjustments.
+	 * On most platforms, the kernel is already relocated, but we still
+	 * want to apply offset adjustments.  For PowerPC, the kernel is
+	 * ET_DYN rather than ET_EXEC and we still need to relocate here.
 	 */
-	if (ef->kernel)
+	if (ef->kernel && ef->ehdr->e_type != ET_DYN)
 		return (EOPNOTSUPP);
 
 	for (n = 0; n < ef->relsz / sizeof(r); n++) {