ARC: Remove non existent refs to GENERIC_KERNEL_EXECVE & GENERIC_KERNEL_THREAD

This tracks mainline commit ae903caa "Bury the conditionals from
kernel_thread/kernel_execve series" which we missed out as ARC port was
not yet mainline.

[vgupta: commit log modified]
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/Kconfig

@@ -16,8 +16,6 @@ config ARC
 	select GENERIC_FIND_FIRST_BIT
 	# for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
 	select GENERIC_IRQ_SHOW
-	select GENERIC_KERNEL_EXECVE
-	select GENERIC_KERNEL_THREAD
 	select GENERIC_PENDING_IRQ if SMP
 	select GENERIC_SMP_IDLE_THREAD
 	select HAVE_ARCH_KGDB