part: show efi partition name when print out partition info

Previous output:
Marvell>>  mmc part

Partition Map for MMC device 1  --   Partition Type: EFI

Part  Start LBA  End LBA
gpt1  0x8C00    0xCBFF
gpt2  0xCC00    0x57BFF
gpt3  0x57C00    0xA2BFF
gpt4  0xA2C00    0xECBFDE

With the patch, the output becomes:
Marvell>> mmc part

Partition Map for MMC device 1  --   Partition Type: EFI

Part    Name                    Start LBA       End LBA
  1     ramdisk                 0x00008C00      0x0000CBFF
  2     system                  0x0000CC00      0x00057BFF
  3     userdata                0x00057C00      0x000A2BFF
  4     remaining               0x000A2C00      0x00ECBFDE

Signed-off-by: Lei Wen <leiwen@marvell.com>
diff --git a/disk/part_efi.h b/disk/part_efi.h
index 6bbb06b..5903e7c 100644
--- a/disk/part_efi.h
+++ b/disk/part_efi.h
@@ -117,13 +117,14 @@
 	unsigned long long type_guid_specific:16;
 } __attribute__ ((packed)) gpt_entry_attributes;
 
+#define PARTNAME_SZ	(72 / sizeof(efi_char16_t))
 typedef struct _gpt_entry {
 	efi_guid_t partition_type_guid;
 	efi_guid_t unique_partition_guid;
 	unsigned char starting_lba[8];
 	unsigned char ending_lba[8];
 	gpt_entry_attributes attributes;
-	efi_char16_t partition_name[72 / sizeof(efi_char16_t)];
+	efi_char16_t partition_name[PARTNAME_SZ];
 }
 __attribute__ ((packed)) gpt_entry;