kernel: add bcm47xxpart patch fixing parsing with some TRX formats

This fixes parsing partition placed after TRX with block-aligned length.
It's important e.g. for Archer C9 which has TRX with kernel only and
rootfs as separated partition.

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

target/linux/generic/patches-4.4/143-mtd-bcm47xxpart-fix-parsing-first-block-after-aligne.patch

+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Subject: [PATCH] mtd: bcm47xxpart: fix parsing first block after aligned TRX
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+After parsing TRX we should skip to the first block placed behind it.
+Our code was working only with TRX with length not aligned to the
+blocksize. In other cases (length aligned) it was missing the block
+places right after TRX.
+
+This fixes calculation and simplifies the comment.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+---
+ drivers/mtd/bcm47xxpart.c | 10 ++++------
+ 1 file changed, 4 insertions(+), 6 deletions(-)
+
+--- a/drivers/mtd/bcm47xxpart.c
++++ b/drivers/mtd/bcm47xxpart.c
+@@ -229,12 +229,10 @@ static int bcm47xxpart_parse(struct mtd_
+ 
+ 			last_trx_part = curr_part - 1;
+ 
+-			/*
+-			 * We have whole TRX scanned, skip to the next part. Use
+-			 * roundown (not roundup), as the loop will increase
+-			 * offset in next step.
+-			 */
+-			offset = rounddown(offset + trx->length, blocksize);
++			/* Jump to the end of TRX */
++			offset = roundup(offset + trx->length, blocksize);
++			/* Next loop iteration will increase the offset */
++			offset -= blocksize;
+ 			continue;
+ 		}
+