firmware-utils: mktplinkfw2: update firmware header

1) Be consistent and use tabs
2) Drop FIXME from boot comments - some images use these fields normally

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

tools/firmware-utils/src/mktplinkfw2.c

@@ -56,8 +56,8 @@ struct fw_header {
 	uint32_t	kernel_len;			/* 0x78: kernel data length */
 	uint32_t	rootfs_ofs;			/* 0x7c: rootfs data offset */
 	uint32_t	rootfs_len;			/* 0x80: rootfs data length */
-	uint32_t	boot_ofs;	/* 0x84: FIXME: seems to be unused */
+	uint32_t	boot_ofs;			/* 0x84: bootloader offset */
-	uint32_t	boot_len;	/* 0x88: FIXME: seems to be unused */
+	uint32_t	boot_len;			/* 0x88: bootloader length */
 	uint16_t	unk4;				/* 0x8c: 0x55aa */
 	uint8_t		sver_hi;			/* 0x8e */
 	uint8_t		sver_lo;			/* 0x8f */