flashchips: Add STM M28F256

Very simple 5V, 12V Vpp, 256kbit parallel flash.

Datasheet used:
https://www.mouser.com/catalog/specsheets/STMicroelectronics_M28F256.pdf

Change-Id: I95a59d0b36a9a99e102788bd9c850bf12192efba
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/522
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/82802ab.c b/82802ab.c
index c958f04..0af5d28 100644
--- a/82802ab.c
+++ b/82802ab.c
@@ -117,7 +117,7 @@
 	if (chip)
 		return probe_82802ab_generic(par, chip->total_size * KiB, chip->feature_bits);
 
-	for (chip_size = 256*KiB; chip_size <= 2*MiB; chip_size *= 2) {
+	for (chip_size = 32*KiB; chip_size <= 2*MiB; chip_size *= 2) {
 		*next_ptr = probe_82802ab_generic(par, chip_size, 0);
 		if (*next_ptr)
 			next_ptr = &(*next_ptr)->next;