Remove the redundant/wrong write of 'recovery_as_boot='.

The deleted lines contain a bug that only writes "recovery_as_boot="
into META/misc_info.txt when the value is empty. The issue has no real
impact though, because a) it's no-op for targets not using
BOARD_USES_RECOVERY_AS_BOOT (e.g. non-A/B targets); b) for targets with
BOARD_USES_RECOVERY_AS_BOOT := true, the value gets written correctly as
part of the call to 'generate-userimage-prop-dictionary'.

Test: `m dist` on aosp_bullhead-userdebug. The line is gone from
      META/misc_info.txt.
Test: `m dist` on aosp_marlin-userdebug. 'recovery_as_boot=true' exists
      in META/Misc_info.txt.
Change-Id: I9b4d70d457e141aa308ba2e62e2033602c8012de
diff --git a/core/Makefile b/core/Makefile
index 4ef0d89..97f4252 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2416,9 +2416,6 @@
 ifdef BOARD_BOOTIMAGE_PARTITION_SIZE
 	$(hide) echo "boot_size=$(BOARD_BOOTIMAGE_PARTITION_SIZE)" >> $(zip_root)/META/misc_info.txt
 endif
-ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),)
-	$(hide) echo "recovery_as_boot=$(BOARD_USES_RECOVERY_AS_BOOT)" >> $(zip_root)/META/misc_info.txt
-endif
 ifeq ($(INSTALLED_RECOVERYIMAGE_TARGET),)
 	$(hide) echo "no_recovery=true" >> $(zip_root)/META/misc_info.txt
 endif