microblaze: Add __ucmpdi2() helper function

Add missing __ucmpdi2 helper function.

Error log:
kernel/built-in.o: In function `print_graph_duration':
: undefined reference to `__ucmpdi2'
kernel/built-in.o: In function `print_graph_duration':
: undefined reference to `__ucmpdi2'

Based on MIPS code.

Signed-off-by: Michal Simek <[e-mail]>

arch/microblaze/lib/Makefile

···
 lib-y += modsi3.o
 lib-y += muldi3.o
 lib-y += mulsi3.o
+lib-y += ucmpdi2.o
 lib-y += udivsi3.o
 lib-y += umodsi3.o

arch/microblaze/lib/ucmpdi2.c

···
+#include <linux/module.h>
+
+#include "libgcc.h"
+
+word_type __ucmpdi2(unsigned long long a, unsigned long long b)
+{
+	const DWunion au = {.ll = a};
+	const DWunion bu = {.ll = b};
+
+	if ((unsigned int) au.s.high < (unsigned int) bu.s.high)
+		return 0;
+	else if ((unsigned int) au.s.high > (unsigned int) bu.s.high)
+		return 2;
+	if ((unsigned int) au.s.low < (unsigned int) bu.s.low)
+		return 0;
+	else if ((unsigned int) au.s.low > (unsigned int) bu.s.low)
+		return 2;
+	return 1;
+}
+EXPORT_SYMBOL(__ucmpdi2);