Quick fix for broken writes on FT2232H based programmers

Not sure if this is the final/correct fix, but for now it definately
fixes writes on FT2232H hardware. I have tested this on both, the
DLP Design DLP-USB1232H, and the openbiosprog-spi hardware.

Thanks to Joshua Roys <roysjosh@gmail.com> for the hint on IRC.

Corresponding to flashrom svn r1190.
Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

ft2232_spi.c

@@ -195,7 +195,7 @@ int ft2232_spi_init(void)
 		msg_perr("Unable to set latency timer\n");
 	}
 
-	if (ftdi_write_data_set_chunksize(ftdic, 512)) {
+	if (ftdi_write_data_set_chunksize(ftdic, 256)) {
 		msg_perr("Unable to set chunk size\n");
 	}