[linux-kernel]: correct kernel package name for armhf (#6751)

armhf kernel package name does not have `unsigned` string

Signed-off-by: Guohan Lu <lguohan@gmail.com>

rules/linux-kernel.mk

@@ -18,5 +18,9 @@ SONIC_MAKE_DEBS += $(LINUX_HEADERS_COMMON)
 LINUX_HEADERS = linux-headers-$(KVERSION)_$(KERNEL_VERSION)-$(KERNEL_SUBVERSION)_$(CONFIGURED_ARCH).deb
 $(eval $(call add_derived_package,$(LINUX_HEADERS_COMMON),$(LINUX_HEADERS)))
 
-LINUX_KERNEL = linux-image-$(KVERSION)-unsigned_$(KERNEL_VERSION)-$(KERNEL_SUBVERSION)_$(CONFIGURED_ARCH).deb
+ifeq ($(CONFIGURED_ARCH), armhf)
+	LINUX_KERNEL = linux-image-$(KVERSION)_$(KERNEL_VERSION)-$(KERNEL_SUBVERSION)_$(CONFIGURED_ARCH).deb
+else
+	LINUX_KERNEL = linux-image-$(KVERSION)-unsigned_$(KERNEL_VERSION)-$(KERNEL_SUBVERSION)_$(CONFIGURED_ARCH).deb
+endif
 $(eval $(call add_derived_package,$(LINUX_HEADERS_COMMON),$(LINUX_KERNEL)))