MIPS: Prevent link failure with kcov instrumentation

__sanitizer_cov_trace_pc() is not linked in and causing link
failure if KCOV_INSTRUMENT is enabled. Fix this by disabling
instrumentation for compressed image.
Signed-off-by: Jouni Hogander <jouni.hogander@unikie.com>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: linux-mips@vger.kernel.org

arch/mips/boot/compressed/Makefile

@@ -29,6 +29,9 @@ KBUILD_AFLAGS := $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
 	-DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) \
 	-DKERNEL_ENTRY=$(VMLINUX_ENTRY_ADDRESS)
 
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT		:= n
+
 # decompressor objects (linked with vmlinuz)
 vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o