Fix erase for SST49LF020A

The chip supports multiple erase functions, but the function we use has
an eraseblock size of 4k.

Corresponding to flashrom svn r664.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
diff --git a/flashchips.c b/flashchips.c
index fa5fdff..e6b86a0 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -2160,7 +2160,7 @@
 		.manufacture_id	= SST_ID,
 		.model_id	= SST_49LF020A,
 		.total_size	= 256,
-		.page_size	= 16 * 1024,
+		.page_size	= 4 * 1024,
 		.tested		= TEST_UNTESTED,
 		.probe		= probe_jedec,
 		.probe_timing	= 1,			/* 150 ns */