arm: mvebu: Update name of kwbimage v1 field at offset 0x2-0x3

At this offset is stored nand page size.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>

cmd/mvebu/bubt.c

@@ -89,7 +89,7 @@ struct mvebu_image_info {
 struct a38x_main_hdr_v1 {
 	u8  blockid;               /* 0x0       */
 	u8  flags;                 /* 0x1       */
-	u16 reserved2;             /* 0x2-0x3   */
+	u16 nandpagesize;          /* 0x2-0x3   */
 	u32 blocksize;             /* 0x4-0x7   */
 	u8  version;               /* 0x8       */
 	u8  headersz_msb;          /* 0x9       */