kbuild: Fix KERNELVERSION for empty SUBLEVEL or PATCHLEVEL

Omit the second dot for releases without SUBLEVEL. If PATCHLEVEL is also
empty, only display VERSION.
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -378,7 +378,7 @@ KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds
 
 # Read KERNELRELEASE from include/config/kernel.release (if it exists)
 KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
-KERNELVERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
+KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
 
 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
 export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC