lib: sbi: Print scratch size and usage at boot time

The scratch space being a scarce resource so let us print it's
size and usage at boot time.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

lib/sbi/sbi_scratch.c

@@ -97,3 +97,14 @@ void sbi_scratch_free_offset(unsigned long offset)
 	 * brain-dead allocator.
 	 */
 }
+
+unsigned long sbi_scratch_used_space(void)
+{
+	unsigned long ret = 0;
+
+	spin_lock(&extra_lock);
+	ret = extra_offset;
+	spin_unlock(&extra_lock);
+
+	return ret;
+}