Kconfig: Add missing quotes around source file

All errors are generated by ./tools/qconfig.py -b -j8 -i whatever.
Error look like this:
drivers/crypto/Kconfig:9: warning: style: quotes recommended around
'drivers/crypto/nuvoton/Kconfig' in 'source drivers/crypto/nuvoton/Kconfig'

Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/arch/arm/mach-rockchip/rv1126/Kconfig b/arch/arm/mach-rockchip/rv1126/Kconfig
index 55b1112..ae323ee 100644
--- a/arch/arm/mach-rockchip/rv1126/Kconfig
+++ b/arch/arm/mach-rockchip/rv1126/Kconfig
@@ -64,7 +64,7 @@
 config TEXT_BASE
 	default 0x600000
 
-source board/edgeble/neural-compute-module-2/Kconfig
-source board/itead/sonoff-ihost/Kconfig
+source "board/edgeble/neural-compute-module-2/Kconfig"
+source "board/itead/sonoff-ihost/Kconfig"
 
 endif