xtensa: enable KCOV support

Select ARCH_HAS_KCOV and set KCOV_INSTRUMENT = n inside
arch/xtensa/boot/lib.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Documentation/features/debug/kcov/arch-support.txt

@@ -27,5 +27,5 @@
     |       sparc: | TODO |
     |          um: |  ok  |
     |         x86: |  ok  |
-    |      xtensa: | TODO |
+    |      xtensa: |  ok  |
     -----------------------

arch/xtensa/Kconfig

@@ -6,6 +6,7 @@ config XTENSA
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DMA_PREP_COHERENT if MMU
+	select ARCH_HAS_KCOV
 	select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
 	select ARCH_HAS_DMA_SET_UNCACHED if MMU

arch/xtensa/boot/lib/Makefile

@@ -17,6 +17,7 @@ endif
 
 KASAN_SANITIZE := n
 KCSAN_SANITIZE := n
+KCOV_INSTRUMENT := n
 
 CFLAGS_REMOVE_inflate.o += -fstack-protector -fstack-protector-strong
 CFLAGS_REMOVE_zmem.o += -fstack-protector -fstack-protector-strong