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 --git a/arch/frv/kernel/Makefile b/arch/frv/kernel/Makefile
index ad4087b..7b10bc1 100644
--- a/arch/frv/kernel/Makefile
+++ b/arch/frv/kernel/Makefile
@@ -7,7 +7,7 @@
 
 extra-y:= head.o vmlinux.lds
 
-obj-y := $(heads-y) entry.o entry-table.o break.o switch_to.o kernel_thread.o \
+obj-y := $(heads-y) entry.o entry-table.o break.o switch_to.o \
 	 kernel_execve.o process.o traps.o ptrace.o signal.o dma.o \
 	 sys_frv.o time.o setup.o frv_ksyms.o \
 	 debug-stub.o irq.o sleep.o uaccess.o