frv: split ret_from_fork, simplify kernel_thread() a lot

Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc arch/frv/kernel/Makefile
Simple merge

diff --cc arch/frv/kernel/entry.S
Simple merge

diff --cc arch/frv/kernel/frv_ksyms.c
Simple merge

diff --cc arch/frv/kernel/kernel_thread.S
Simple merge

diff --cc arch/frv/kernel/process.c
Simple merge