mtd: bcm47xxpart: lower minimal blocksize to 4Ki (from 64Ki)

Some devices like Netgear WNR1000v3 or WGR614v10 have partitions aligned
to 0x1000. Using bigger blocksize stopped us from detecting some parts.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/bcm47xxpart.c b/drivers/mtd/bcm47xxpart.c
index 26a4a4a..4ad3928 100644
--- a/drivers/mtd/bcm47xxpart.c
+++ b/drivers/mtd/bcm47xxpart.c
@@ -94,8 +94,12 @@
 	int last_trx_part = -1;
 	int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 
-	if (blocksize <= 0x10000)
-		blocksize = 0x10000;
+	/*
+	 * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
+	 * partitions were aligned to at least 0x1000 anyway.
+	 */
+	if (blocksize < 0x1000)
+		blocksize = 0x1000;
 
 	/* Alloc */
 	parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,