kernel: fix flock name for gen-initramfs lock

Fix flock name for gen-initramfs lock as $(2) starts with .HASH making
the lock name gen-initramfs-.HASH.flock

Fix this to a better name of gen-initramfs.HASH.flock

Fixes: 52cc9d82f113 ("kernel: rework Initramfs locking logic")
Signed-off-by: Christian Marangi <[email protected]>

include/kernel-defaults.mk

@@ -214,7 +214,7 @@ define Kernel/CompileImage/Initramfs
 			$(KERNEL_MAKE) $(if $(2),-C $(LINUX_DIR)$(2)) $(KERNEL_MAKEOPTS_IMAGE) $(if $(KERNELNAME),$(KERNELNAME),all);) \
 		$(call Kernel/CopyImage,-initramfs,$(2)); \
 		$(if $(2),rm -rf $(LINUX_DIR)$(2);) \
-	}, gen-initramfs$(if $(2),-$(2)));
+	}, gen-initramfs$(2));
 endef
 else
 define Kernel/CompileImage/Initramfs