part: efi: comment for GPT_HEADER_SIGNATURE_UBOOT

Add a comment indicating that the value of GPT_HEADER_SIGNATURE_UBOOT
equals the ASCII string 'EFI PART'.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/part_efi.h b/include/part_efi.h
index eb5797a..1929e44 100644
--- a/include/part_efi.h
+++ b/include/part_efi.h
@@ -24,7 +24,7 @@
 #define EFI_PMBR_OSTYPE_EFI 0xEF
 #define EFI_PMBR_OSTYPE_EFI_GPT 0xEE
 
-#define GPT_HEADER_SIGNATURE_UBOOT 0x5452415020494645ULL
+#define GPT_HEADER_SIGNATURE_UBOOT 0x5452415020494645ULL // 'EFI PART'
 #define GPT_HEADER_CHROMEOS_IGNORE 0x454d45524f4e4749ULL // 'IGNOREME'
 
 #define GPT_HEADER_REVISION_V1 0x00010000