package/perf: fix build failures with high 'make -j' values

The 'perf' Makefile is flaky on some kernel versions. It will still parallelize
the build even with 'make -j1' because it explicitly invokes a sub-make with
the correct flags. But the top-level make is not smart enough to handle large
'-j' values.

Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/perf/perf.mk

@@ -53,14 +53,14 @@ define PERF_BUILD_CMDS
 			fi \
 		fi \
 	fi
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(LINUX_DIR)/tools/perf \
+	$(TARGET_MAKE_ENV) $(MAKE1) -C $(LINUX_DIR)/tools/perf \
 		$(PERF_MAKE_FLAGS) O=$(@D)
 endef
 
 # After installation, we remove the Perl and Python scripts from the
 # target.
 define PERF_INSTALL_TARGET_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(LINUX_DIR)/tools/perf \
+	$(TARGET_MAKE_ENV) $(MAKE1) -C $(LINUX_DIR)/tools/perf \
 		$(PERF_MAKE_FLAGS) O=$(@D) install
 	$(RM) -rf $(TARGET_DIR)/usr/libexec/perf-core/scripts/
 endef