sd-gpt: __mips__ is also defined when building __mips64

Follow-up for d75ec33

(cherry picked from commit c26a01a)
(cherry picked from commit 908463c)

Author: bluca

src/systemd/sd-gpt.h

@@ -216,7 +216,7 @@ _SD_BEGIN_DECLARATIONS;
 #  define SD_GPT_USR_NATIVE_VERITY SD_GPT_USR_LOONGARCH64_VERITY
 #  define SD_GPT_USR_NATIVE_VERITY_SIG SD_GPT_USR_LOONGARCH64_VERITY_SIG
 
-#elif defined(__mips__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#elif defined(__mips__) && !defined(__mips64) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 #  define SD_GPT_ROOT_NATIVE SD_GPT_ROOT_MIPS_LE
 #  define SD_GPT_ROOT_NATIVE_VERITY SD_GPT_ROOT_MIPS_LE_VERITY
 #  define SD_GPT_ROOT_NATIVE_VERITY_SIG SD_GPT_ROOT_MIPS_LE_VERITY_SIG