tools: Make kwboot build if HOST_TOOLS_ALL=y

The kwboot tool for Marvell devices isn't currently being built even if
HOST_TOOLS_ALL is set. It doesn't appear to depend on any CONFIG_
options, so it seems appropriate to enable building it here.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
diff --git a/tools/Makefile b/tools/Makefile
index 55efb74..8143c25 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -7,6 +7,7 @@
 
 # Enable all the config-independent tools
 ifneq ($(HOST_TOOLS_ALL),)
+CONFIG_KIRKWOOD = y
 CONFIG_LCD_LOGO = y
 CONFIG_CMD_LOADS = y
 CONFIG_CMD_NET = y