um: put power options in a menu

Because having them all dumped at top-level is a bit messy.
Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/Kconfig

@@ -243,4 +243,8 @@ source "arch/um/drivers/Kconfig"
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
 
+menu "Power management options"
+
 source "kernel/power/Kconfig"
+
+endmenu