disk: include errno.h explicitly in part.h

Some errno numbers are used in defining inline functions.
So "errno.h" should be explicitly included to avoid possible build errors.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

include/part.h

@@ -10,6 +10,7 @@
 #include <ide.h>
 #include <uuid.h>
 #include <linker_lists.h>
+#include <linux/errno.h>
 #include <linux/list.h>
 
 struct block_drvr {