Fix A25L40PU and A2540PT due to incorrect full-chip block size is incorrect

Corresponding to flashrom svn r865.

Thanks to hailfinger's self-check-erase routine for catching this.
Signed-off-by: Sean Nelson <audiohacked@gmail.com>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

flashchips.c

@@ -1181,7 +1181,7 @@ struct flashchip flashchips[] = {
 				},
 				.block_erase = spi_block_erase_d8,
 			}, {
-				.eraseblocks = { {256 * 1024, 1} },
+				.eraseblocks = { {512 * 1024, 1} },
 				.block_erase = spi_block_erase_c7,
 			}
 		},
@@ -1213,7 +1213,7 @@ struct flashchip flashchips[] = {
 				},
 				.block_erase = spi_block_erase_d8,
 			}, {
-				.eraseblocks = { {256 * 1024, 1} },
+				.eraseblocks = { {512 * 1024, 1} },
 				.block_erase = spi_block_erase_c7,
 			}
 		},